Download Organic Compounds

Organic Compounds
Carbon Atom – 6 Protons, 6 Neutrons, 6 Electrons – Will not for ionic bonds but form covalent bonds instead.
Always forms 4 covalent bonds. Single covalent bond where it shares one pair or double covalent bonds where
it shares two pairs or triple covalent bonds where it shares three pairs.
Figure 1
Hydrocarbons are hydrophobic because they are pure non polar covalent – Will not dissolve in water because
they have not electrical charges
Water is a polar molecule and has electrical charges.
Functional group – Group of atoms that form a unit that acts in a certain way. Page 34
Hydroxl - OH polar H is + and O is Carboxl - COOH polar
Amino Group - NH2 proteins
Phosphate groups
- PO4 polar
Sulfhydryl
- SH proteins
Adding these groups onto hydrocarbon chains will change how they function and make important organic
molecules -- organic macromolecules
Organic Macromolecules
-Most are polymers (a large molecule made of repeating subunits (Monomers)) made out of monomers
Two reactions:
Dehydration reactions Figure 2 monomers chain of monomers started and you lose a water – anabolic and
endergonic
Hydrolysis – breaking polymers apart to form monomers Figure 3 - catabolic and exergonic
Types of macromolecules
Carbohydrates – composed of monomers - the basic unit is a sugar or a (monosaccharaide) or two sugars is a
disaccaharide, trisaccaharide, polysaccharide
Most simple sugars have a carbon ring as their basis
Dehydration – For ever one carbon, there will be 2 hydrogens and 1 oxygen
Glucose is a monosaccharide C6H12O6 or 1:2:1 (carbon to hydrogen to oxygen ratio) can also be fructose
Starch is polysaccharide – plants long term energy storage composed of a chain of glucoses
Glycogen is the animal long tern energy storage molecule and is also composed of glucoses
Cellulose is used for plant cell walls, and is a dietary fiber, composed of glucoses
Lipids (second type of macromolecule) oily consistency and are mostly hydrophobic
- fats (triglycerides) made of monomers called glycerol and fatty acids
- phospholipids (cell membranes)
- steroids not made of monomers
triglyceride Figure 4 combines with three different fatty acids (hydrocarbon chain 16-22 carbons long and nonpolar so it won’t be able to dissolve in water) attach and they release 3 water molecules
- can be saturated with hydrogen because it is has the most possible Figure 5
- unsaturated is the bent chain… it doesn’t have the maximum amount of hydrogens
phospholipids – polar area attached to glycerol backbone (hydrophilic) and a fatty acid tail that is non-polar
(hydrophobic)
steroids – have 4 linked rings of carbons (hydrophobic and oily) are not composed of monomers
cholesterol is the precursor for all steroids (all steroids begin with cholesterol)
proteins are made of repeated subunits made of amino acids
each amino acid has this structure amino group bound to a central carbon (with on hydrogen) and bound to a
carboxyl group and bound to “R” the side group Figure 6 amino acids vary by their side groups
- some side groups are very hydrophilic (dissolve in water in water or attracted to water)
- some are hydrophobic (hydrocarbon rings)
- ones with sulfur groups (forms disulfide ridges)
- 20 amino acids
proteins
- important structural components (hair and nails, cytoskeleton (microtubials))
- enzymes (control every chemical reaction in you body) (most abundant)
peptide bond
- bond between the carbon of the carboxyl group and the nitrogen of the amino group (method in which
the proteins get their name)
- dipeptide
- tripeptide
- polypeptide
protein shape is very important. Levels of protein shape:
- primary – sequence of amino acids in a polypeptide
- secondary – helix or pleated sheets (fan folded paper) Caused by hydrogen bonding between the amino
acids
- tertiary – further folding of the protein. Caused by chemical interactions between the side groups
- quaternary – two or more polypeptides binding or fitting together (hemoglobin (carries oxygen) made of
four polypeptides
nucleic acids – contain the hereditary material
- forms of monomers called nucleotides
o five carbon sugar C5H10O5
o phosphate group
o nitrogen base
- backbone of a dna molecule is alternating series of phosphates and 5 carbon sugars
- nitrogen bases are attached to the five carbon sugars
- cytosine, thymine, adenine, guanine are in DNA (bases)
Photosynthesis
- green plants – algae (protests, single celled), cyanobacteria (has the ability to do photosynthesis but
doesn’t have chloroplasts because they are prokaryotes)
- chloroplasts have a inner membrane known as the thylakoid membrane and the space between the
thylakoid membrane and the inner membrane is called a stroma (fluid filled)
- chloroplasts are found in mesophyl cells
- the visible light spectrum is best at getting through the atmosphere
- light capture excites electrons in a pigment molecule – electrons move out an energy level
- the wavelengths of light have different amounts of energy
- the amount of energy that a wave length of light has one quantum of energy
- the shorter the wavelength, the more energy
- chlorophyll is the primary energy absorbing pigment in plants
- they absorb either sides of green but reflects green back – absorbs 500 ad 500 – reflects 525
Equation of photosynthesis
- 6CO2 + 6H2O  C6H12O6 + 6O2
anabolic and endergonic
- light dependant reaction – requires light energy – occurs in thylakoid membrane
Light energy is captured and converted into chemical energy
- light independent reaction – doesn’t require light – occurs in stroma
energy is converted into longer term storage molecules
Photosystem – “antenna” complexes of pigments Figure 6
- chlorophyll a at “reaction center”
- hands off electron to an election acceptor molecule
- figure 7-4 in book
Non-cyclic electron flow
- photosystem 2 accepts light energy
- electron is transferred from the reaction center to the electron acceptor molecule
- electrons are replaced by splitting a water molecule 2H2O  O2 + 4H+
- water is split into oxygen and hydrogen ions
Electron transport system – series of membrane bound molecules which have the ability to pass along electrons
- each time the electron is passed along, it loses a little bit of energy
- energy used to power active transport (pumping particles against a concentration gradient) of H+ against
the concentration gradient into the thylakoid space
- creates an artificially high concentration gradient of hydrogen ions
- a rush of hydrogen ions run back down the concentration gradient by facilitated diffusion back into the
stroma (Chemiosmosis)
o ATP synthase – membrane protein for the facilitated diffusion - channel protein and enzyme ADP + P  ATP highly endergonic
-
photosystem 1 accepts light energy
electron leaves the photosystem to an electron acceptor molecule
electron is replaced by electrons from photosystem 2
energy used to create NADPH energy storage
light dependant reaction
- water  O2 + H+
- H+ used to create gradient to power production of ATP
- Produced NADPH, O2, ATP think of the P in NADPH as P for photosynthesis
Light independent reactions – Calvin cycle
- energy from the light dependant reaction drives a series of reactions to form a carbon base energy
storage molecule
stages of Calvin cycle
- Carbon Dioxide fixation – incorporating a non organic molecule into an organic molecule (make the
molecule into a form usable by living organisms 18 carbons
- Carbon dioxide reduction – series of molecular rearrangements - 6 three-carbon carbohydrates, 1 threecarbon carbohydrate leaves the calvin cycle – PGAL is given off by the Calvin cycle 15 carbons –
requires ATP & NADPH
- Regeneration of original molecules – 5 three-carbon PGAL is converted back into 3 five-carbon
carbohydrates which where the original molecules – requires ATP
Immediate product of photosynthesis is PGAL (C3H6O3)
PGAL + PGAL = glucose (C6H12O6) then starch which is the long term energy storage molecule
Leaves
Air goes into a leaf through a pore called a stoma – if the stoma closes…. You get too much oxygen and too
little carbon dioxide
Photorespiration
It is hot and dry and the stoma is closed. You get a depletion of carbon dioxide and get excess oxygen – the
oxygen is added into the calvin cycle so you end up with two carbon molecules which are unusable
C3 plants are plants that do regular photosynthesis and do not try to work around the photorespiration problem
C4 plants have a way around photorespiration (adapted for dry conditions - grass) – when stoma are open they
incorporate excess carbon dioxide in a four-carbon molecule – the four-carbon molecule is used to store carbon
dioxide – the calvin cycle is in cells called “bundle sheath” cells
Cellular respiration
- Photosynthesis 6CO2 + 6H2O  C6H12O6 + 6O2
- Aerobic cellular respiration - C6H12O6 + 6O2  6CO2 + 6H2O
- All possible metabolic pathways by which carbohydrates or other similar molecules are broken down to
produce ATP
Aerobic cellular respiration
- requires oxygen
- most efficient pathway
- 36 – 38 ATP
- Glycolysis – Breakdown of glucose into two molecules of pryruvate which are three carboned
o Glucose activation
 input of two ATP molecules
o Energy harvest
 Unstable six-carbon molecule breaks into 2 three-carbon molecules
 Rearranges into two pryruvates
 Produces 4 ATP’s and 2 NADH’s and two pryruvates
 Takes place in cytoplasm
- Transition reaction
o Pryrvate turns into CO2 and Acetyl – CoA 2-c produces NADH
o Occurs twice for each original glucose
 2 CO2 – molecular products
 2 Acetyl – COA and two NADH
o Occurs in mitochondrial matrix
- Kreb cycle
o Creates ATP and FADH2 and NADH and releases CO2
o Start with a four-carbon molecule and add in two carbons from acetyl-CoA and creat a sixcarbon molecule , breakoff two CO2 in two different steps resulting in another four-carbon
molecule which will be re arranged back to the original four-carbon molecule
o Molecular products – two carbon dioxides
o Energy products – 3 NADH, 1 FADH2, 1 ATP spins twice
- RECAP
o Glycolysis – 1 six-carbon  1 three-carbon
o Transition – 2 three-carbon  2 two-carbon + 2 CO2
o Krebs – 2 two-carbon  4 CO2
 No more carbons now
- Electron Transport System
o Chemiosmosis
o A series of membrane molecules which have the ability to accept and pass along high energy
electrons
o Oxygen is the final acceptor of the electrons and then it gets a negative charge so it gets attracted
to several hydrogen ions and then water is formed 02- + 4 H+  H20
o Energy from the ETS used to actively pump hydrogen ions from an area of low concentration
(mitochondrial matrix) to an area of high concentration (intermembranous space) creating an
artificially steep concentration gradient
o ATP synthase – membrane protein which both allows the hydrogen ions back across the
membrane and catalyzes the formation of ATP from ADP
o Produces 32-34 ATP
- Aerobic Cellular Respiration
o 36-38 ATP Total
Anaerobic Cell. Respiration
- No oxygen
- Body uses alternate pathways
- Animals produce lactic acid
- Oxygen debt – amount of oxygen necessary to remove the buildup of lactate
- Plants without oxygen go through alcoholic fermentation to produce ethanol + carbon dioxide
Starch - storage carbohydrates in plants
- series of glucose
lipids – triglycerides
- glycerol
- fatty acids – the hydrocarbon chains are broken into a series of two-carbon molecules
remember the amino acid structure
- the “R” is hydrocarbons or carbon containing functional groups
nucleotide – five-carbon sugar that has a nitrogen base and a phosphate group bound to it
CELL DIVISION
3 fates can happen to any cell
- grow and reproduce – cell cycle
- a cell can choose to exit the cell cycle but continue to function
- a cell may choose to die – programmed cell death or apoptosis
two reasons why a cell may choose to grow and reproduce
- reproduction – to produce new organisms
- growth – development of embryos or juveniles
- repair
cell division by bacteria or prokaryotes
binary fission
- prokaryotes have a single circular DNA or chromosome
- DNA duplicates
- Forms two circular chromosomes
- They are attached to the cell membrane
- The cell divides between the two chromosomes
Cell division in eukaryotes
Cell cycle
-
-
Interphase – 90% of its time is spent in interphase – cell does normal activities
o G1 – first growth phase after a previous cell division – grows in size and produces all the
necessary organelles – the cell is doing its job
o S – synthesis of DNA – DNA makes exact copies of itself – chromosomes duplicate
o G2 – a second phase of growth – cell prepares for division – still doing normal job
o A cell at the end of G1 stage must make a go, or no go decision (G0)
 External input about the division decision – growth factors or hormones
 Cell density – too many cells in one spot, or is there enough around
 Transformed cell – can no longer make a correct density decision – tumors
o
Benign tumors – localized areas of growth that are not needed by the
organism – stay confined to an area
o cancers – uncontrolled cell growth – invade other tissues
 metastasize – cells break off and go to other places in the body and
form a new tumor
 G0 Stage – cell exits the cell cycle and not reproduce – nerve cells
mitotic phase – cell division phase
o asexual cell division – for growth or repair – cell division for reproduction if not sexual
o start and end cell division with the same number for chromosomes
o humans have 46 chromosomes
body cells – mitosis
sex cells – located in ovaries or testis – meiosis
Mitosis – karyokenesis – division of the nucleus (chromosomes)
- prophase
- metaphase
- anaphase
- telophase
- cytokinesis – division of the actual cell – telophase overlaps cytokinesis
Prophase
- DNA begins and completely condenses into chromosomes (chromatin – interphase, DNA is in very long
and thin strands)
- twists around proteins
- chromosome has both DNA and proteins
Metaphase
- chromosomes lined up at cell equator and chromosomes aligned roughly at right angles to the direction
of the spindle fibers
Anaphase
- sister chromotids separate and are drawn towards the cell’s pole
Cytokinesis
- cell begins to elongate
- “free” spindle fibers push against each other and begin to force the cell apart
telophase
- opposite events of prophase
- spindle apparatus breaks down
- nuclear envelope reforms
- chromosomes begin to uncondensed
- you get a cell with two reforming nuclei at opposite ends of the cell
cytokinesis (breaking cell apart)
- rings of microfilaments are wrapped around the cell’s equator
- they contract and pinch the cell apart
- cleavage furrowing
- in plant cells, it occurs by forming a cell plate
- vesicles containing cellulose will begin to line up at cell’s equator and will start to fuse
- they form a cell membrane and in between, you have the cellulose
mitosis
- parent cell produces two daughter cells which are identical to each other and to the parent with regards
to the nucleus
Diploid cell – cell with chromosomes in pairs (humans have 46, so there are 23 pairs) (2n=46)
- females have 23 homologous pairs (two chromosomes which contain the same type of genetic
information but not necessarily exactly the same
- males have 22 homologous pair and 1 non-homologous pair, the sex chromosomes X Y
Haploid cell – cell with chromosomes which are not paired (n=23)
Meiosis – the point is to take the diploid number and move it down to the haploid number
Meiosis 1 – homologous pairs separate – FIGURE 7
Meiosis 2 – sister chromotids separate
Meiosis 1
- Prophase 1
o Chromosomes condense around the proteins
o Nuclear envelope breaks down
o Spindle is formed
o Homologous pairs pair up and forms a tetrad
- Metaphase 1
o Homologous pairs line up at the cell’s equator
- Anaphase 1
o Homologous pairs separate and are drawn towards the poles by microtubules of the spindle
apparatus
o Cytokinesis of anaphase 1
 Cell elongates due to free tubules of the spindle apparatus pushing against each other
- Telophase 1
o Chromosomes are at the poles – end up with haploid nuclei area
o Nuclear envelope usually reforms
o Chromosomes may uncondensed – depends on the organism – but humans… it does
o Spindle breaks down
o Cytokinesis events in telophase 1
 Separation of cells into two cells
 Animals – cleavage furrow
 Plants – cell plate
Meiosis 2
- Prophase 2
o If the nuclear envelope reformed in telophase 1, it will break down
o If the chromosomes relaxed during telophase 1, they will condense
o Spindle will reform
o Spindle tubules will attach to individual chromosomes at the centromere
- Metaphase 2
o Chromosomes line up at cell’s equator
- Anaphase 2
o Sister chromotids separate and are moved towards the cells’ poles by the spindle
-
o Cytokinesis of anaphase 2
 Cells elongates by free spindle fibers or tubules
Telophase 2
o Chromosomes at opposite poles
o Chromosomes uncondense
o Spindle will break down
o Nuclear envelope will reform
o Cytokinesis events of telophase 2
 Separation of cells by cleavage furrow or cell plate
We can now have a total of 4 haploid cells as a result of this
Haploid and diploid can go through mitosis
Diploid can only go through meiosis
Spermatogenesis
Testis
- seminiferious tubules – site of spermatogenesis
- epididymus – sperm storage
- Spermatogonia can go through mitosis to replenish spermatogonia and are diploid cell in tubules
- Primary spermatosites – prophase 1 – nuclei stain well
- Secondary spermatosites – nuclei don’t stain well
- Mature sperm cells get flushed though the tubes and get stored in the epididymis until needed
OOGenesis
Ovary
- OOgonium – does not do mitosis (so women have all that they have when they are born)
o Develops in a follicle – nourishes the developing egg cell
- Primary OOcyte – prophase 1 of meiosis – found in a primary follicle – which is small
- Secondary OOcyte – polar body – in females, there is unequal cytoplasmic division
- Secondary oocyte gets released - hopefully find their way into the fallopian tube
- Meiosis 2 happens after fertilization
- Final product is known as a ovum – unequally division, forms polar body, then breaks down
- Fusion of the nuclei and forms a diploid zygote
- The follicle stays around – corpus lutem – hormones for pregnancy
Haploid
- Fungus – diploid life cycle
- Haploid - animals
o produce sperm and egg by mitosis
o fertilization to become a diploid zygote, and then meiosis to form the haploid organism again
plants have alternation of generations – have a adult haploid stage and an adult diploid stage
non disjunction – when meiosis goes wrong
- sometimes a pair fails to separate FIGURE 9
- trisomy 21 – downs syndrome
- monosomy x – only one x sex chromosomes
Gregor Mendel – Mendelian genetics
- inheritance patterns of both animals and plants
- studied a type of pea plant
- studied traits – flower color, plant height, seed color, seed texture
- generally, the characteristics on plants are not linked on a chromosome
- most of his characteristics showed simple dominance and recessiveness
dominance – if two different alleles of a gene are present, one allele will mask the expression of another
recessive – masked by presence of a dominant allele
you have a gene for hair line and have two different forms of that gene known as an allele
pea plants will self fertilize – fertilization will occur while the flower is still shut
pure breeding – if you have white flower and you leave it on it’s on, it will always get a white flower
mendle’s experiments
took pure breeding white flower and purple flower organism and cross fertilized them
all the offspring of the first generation was purple
P generation – parental
F1 generation – first generation offspring (filial – brothers)
His F2 generation were ¾ purple and ¼ white
Law of segregation – alternate forms of a trait separate from each other into different cells
Two alleles of a gene separate into different cells during meiosis 1
Law of independent assortment – manner in which one chromosome or 1 gene separates has no effect on how
another chromosome or gene separates
Dominant and recessive are joined together by chance – DD and RR or DR and DR
Genes – segment of a chromosome which codes for a particular trait
Allele – alternate forms of that gene
Homozygous – both members for the chromosome pair have the same allele form WW
Heterozygous – the members of a chromosome pair do not have the same form of allele Ww
Dominant allele – mask the expression of another allele if the organism is heterozygous
Recessive allele – mask by the presence of a dominant allele if the organism is heterozygous
Homozygous dominant – has the same allele form on both chromosomes and both are dominant alleles
Homozygous recessive – has the same allele form but both are recessive alleles
Genotype – exactly which alleles are present on the chromosomes WW, Ww, ww
Phenotype – what is expressed by the organism (what it looks like) widows peak or straight
Friday, October 10, 2003
Test cross - cross a recessive individual with a phenotypically dominant individual to test what genotype the
dominant individual is FIGURE 10
Normal pigment in skin – Dominant trait AA, Aa - Normal
Albino – Recessive aa – albino recessive
Polydactyl – More than 5 fingers It is actually a dominant trait, if you have 5 fingers, you are recessive (pp)
Huntington’s disease – degeneration of the nervous system – if you heterozygous for it, then you will have it
Incomplete dominance – the heterozygote shows a blending of the two allele types
- combine a red snap-dragon plant with a white one and you can get pink plants
- FIGURE 11
Co-dominance – the heterozygote shows both alleles completely in the phenotype – blending of flower color is
an example, so if you had a red and white striped plant… it would not be co-dominant
Multiple alleles – in a population, there may be more than 2 allele forms, however in an individual, there can be
only 2
Human blood types – FIGURE 12
Antigen is a type of recognition protein
- can be found on cell’s surface
- a carbohydrate chain on a protein is known as a glycoprotein
Rose color – multiple genes and each gene shows incomplete dominance
Monday, October 13, 2003
Linked Genes – genes found on the same chromosomes are said to be linked – cannot assort independently
- offspring do not have ratios common to simple mendelian genetics
- Dihybrid cross – cross between two heterozygous individuals with two genes under consideration
- AaBb – if A & B are on the same chromosome, the phenotypic ratio and genotypic ratio changes
- FIGURE 13
- Genes that are physically further apart on a chromosome are more likely to crossover
Linkage mapping
- recombinant offspring – because crossing over occurred
- the % of recombinant offspring equals the distance on a gene linkage map
- FIGURE 14
Women have 23 homologous pairs and sec chromosomes is XX
Men have 22 homologous pairs and 1 non-homologous XY sex chromosome
If you have the Sry gene, you will be phenotypically is a male
Non disjunction – X and Y chromosome failed to separate so offspring have both sex organs
Genes found on the X chromosome are sex linkage genes
Females could be homozygous or heterozygous AA,aa,Ab
Colorblindness – gene for your ability to see color is found on the X chromosome – baldness, hemophilia
DNA – hereditary material
- isolated late 1800’s from pus bandages from soldiers
- concentrated in nucleus of white blood cell
- when dissolved in water, it acts like an acid
Chromosomes were hereditary material
- DNA – 4 nucleotides
- Protein – 20 amino acids
1950 experiment – Hershey/Chase experiment – Viruses have only DNA as their genetic material
- they incorporated viral DNA into a bacteria and it altered the genetic code, so it was confirmed
Shape or Structure of DNA
- Watson and Crick Model of DNA
- Chargaff discovered that the quantities in DNA of guanine = cytosine
- DNA is a nucleic acid ad are polymers of nucleotides
- FIGURE 15
- Chargaff’s principle – Quantity of guanine = Qty. of Cytosine and Qty. Thymine = Qty. Adenine
- Maurice Wilken’s and Rosalind Franklin – Did X-Ray diffraction of DNA molecule pg. 152
- Double Helix – has two strands
o Uprights (backbone) of the DNA ladder are composed of alternating phosphate and 5-car sugar
o Rungs of the DNA are composed of nitrogen base pairs G-C T-A
o The strands twisted around each other
- Nobel prize was won by – Watson, Crick, and Wilkens
- Atoms other than carbon that are covalently bonded to hydrogens, are often polar covalent bonds
Hereditary molecules must be able to replicate – asexual reproduction
Also must be able to direct protein synthesis – control the cell, tell what proteins to be made and when - enzyme
And most be able to mutate – evolve
- in order for a mutation to get into the next generation, it must be a mutation to a sex cell
DNA replication
1. Initiation
a. Unwinding and Unzipping of DNA
b. Done by a protein called a DNA helicase – breaks hydrogen bonds
c. DNA polymerase attaches to the molecule
i. Takes three nucleotides and begins base pairing to the template strand
2. Elongation – DNA polymerase joins nucleotides together to form a new strand
a. Leading strand – New strand which follows DNA helicase down the replication fork
b. Lagging strand – New strand of DNA which is formed in short segments and must wait for the
replication fork (two DNA strands are anti-parallel)
c. DNA ligase – puts short strands of DNA together on the lagging strand
3. Termination – when the last nucleotide is reached, DNA prolymerase detaches and the two new DNA
molecules are formed
Type of replication is called semi-conservative – new DNA molecule has one old and one new strand
DNA doesn’t leave the nucleus
Transcription – Take DNA and transcribe it to Codons of RNA
RNA – directly responsible for protein sythesis
- created by DNA (from code on DNA)
DNA
Double stranded
Deoxyribose
Nitron bases
-Adenine
-Guanine
-Cytosine
-Thymine
Does not leave nucleus
-except in prokaryotes
-celldivision
RNA
Single Stranded
Ribose
Nitrogen bases
-Adenine
-Guanine
-Cytosine
-Uracil
Can leave nucleus
3Types of RNA
- mRNA – messenger RNA (Carry genetic code as codons to the cytoplasm)
- rRNA – Ribosomal RNA (site of polypeptide synthesis)
- tRNA – transfer RNA (carries amino acids to the ribosomes to match with mRNA codons
o has three exposed nucleotides forming anit-codons
Transcription – make a mRNA molecule using DNA as a template
- only transcribe one gene at a time (although multiple transcriptions may occur simultaneously)
1. Initiation
a. RNA polymerase binds to DNA and unwinds and separates the DNA strands exposing the DNA
nucleotides
b. Begins pairing RNA nucleotides in the nucleus to one strand of the DNA
c. The strand that will be transcribed is called the sense strand and carries the genetic code
2. Elongation
a. RNA polymerase base pairs more RNA nucleotides to DNA and elongates the mRNA strand
b. Adenine gets paired with uracil
3. Termination
a. Something must single transcription to end
b. TATA box – Singles end of transcription (lots of thymine and adenine)
c. You now have the mRNA molecule of an entire gene
Translation – making a polypeptide from the codons of mRNA
1. Initiation
a. tRNA carrying the amino acid methionine binds to the ribosomal RNA
i. Ribosomal RNA has two subunits (small and large
ii. A mRNA molecule will be sandwiched between the two subunits
iii. The large subunits has three important areas
iv. Two sites for binding tRNA and a catalytic site for forming bonds between amino acids
b. The mRNA molecule will base pair its first codon to the tRNA molecule
c. Large subunit attaches and sandwiches the mRNA
2. Elongation
a. A second tRNA molecule with its amino acid binds to the second site of the rRNA
3. Termination
a. Elongation continues until a tRNA with now amino acids base pairs to a codon – stop codons
b. The whole complex breaks apart and the polypeptide is formed
Translation
- polypeptide
- then it takes on a 3-D shape to be an active protein
How cell regulates proteins that are formed
- gene regulation – controls which genes are transcribed
- can control the rate at which they are translated
- the environment in which the proteins are formed can be changed (acidic vs. basic environment)
- moon lightning proteins – change their shape