Download Unit 8b-Modern Genetics

Unit 8b­Modern Genetics
8b.
Modern Genetics
i. Scientists
ii. Nucleic Acids DNA/RNA – Function
iii.Replication
iv. Protein Synthesis
v. Mutations (gene and chromosomal)
vi. Biotechnology
vii. Genetic Engineering
A. Biochemistry Review
1. What are the four organic macromolecules and their building blocks?
Macromolecule
Building Blocks
Carbohydrates
Simple sugars
Lipids
Fatty acid and glycerol
Nucleic Acids
Nucleotides
Proteins
Amino acids
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Unit 8b­Modern Genetics
2. How do we combine the building blocks to make macromolecules?
Dehydration Synthesis
3. Give an example of a reason WHY we would want to make macromolecules.
Storage, Replicate DNA, make Proteins
4. How do we separate macromolecules into their smaller building blocks?
Hydrolysis
5. Give an example of a reason why we would want to break down into building blocks?
Digestion (make molecules small enough to pass across cell membrane
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Unit 8b­Modern Genetics
We'll focus this unit mostly on proteins and nucleic acids, because they play a very important role in modern genetics
Nucleic Acids
Proteins
6. Proteins:
­ Enzymes, hormones, antibodies, hair, pigment, structural components of cell (membrane).
­ ex. hemoglobin, insulin, fibrin, actin/myosin, catalase, and many more (Proteins usually end in ­ase/­in
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Unit 8b­Modern Genetics
7. Nucleic Acids:
a. What are they?
DNA:
Deoxyribonucleic acid
RNA: Ribonucleic acid
b. What do they do?
Store and Transmit genetic material or information
c. What is the structure of a nucleotide?
8. What is DNA?
a. Genetic (hereditary) material
Draw and Label
DNA molecule,
including
showing a gene
b. In Eukaryotic Cells­ Nucleus
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Unit 8b­Modern Genetics
9. How do we know the structure of DNA?
a. Griffith and Avery
­Chemical from one cell is able to genetically transform another cell
b. Hershey and Chase
DNA is the genetic material,
not Proteins
c. Chargaff
A = T
G = C
d. Wilkins and Franklin
X­ray crystallography
Picture of DNA helix
e. Watson and Crick
developed first model of DNA structure
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Unit 8b­Modern Genetics
Let's take a minute (in 1953 that is):
at this point (thanks to
Wilkins, Franklin, Watson, and Crick, we have:
­ a proposed structure of DNA
­ a hypothesis for DNA replication
We still don't have:
­ Proof of a method of DNA replication
­ how DNA worked as the genetic code
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Unit 8b­Modern Genetics
Type of RNA
Abbreviation
Function
Picture
carries the message (recipe)
messenger RNA mRNA
to make the proteins from
the nucleus (DNA) to the
ribosomes
ribosomal RNA
rRNA
makes up the
ribosomes
carries amino acids to
transfer RNA
tRNA
the ribosome so that
proteins can be made
Human DNA Facts
3 billion base pairs
DNA in one cell stretched out­ 2m Long!!!
DNA in all your trillions of cells put together would be about twice the diameter of the solar system!
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Unit 8b­Modern Genetics
*How does all of this DNA fit into a microscopic cell?
http://www.pbs.org/wgbh/nova/genome/dna_flash.html
12. How does DNA carry the Genetic Code?
Nitrogen bases come together and create a pattern...
the instructions for making a gene that will carry the code for making a specific protein
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Unit 8b­Modern Genetics
13. Genes:
• Sections of DNA
• Every gene has a specific genetic code
• Genes code for our traits
• There are an estimated 20,000­25,000 human protein­coding genes.
14. Complementary base pairs:
*Can you identify the complementary nitrogen bases that match up with those located on the DNA strand below?
C A T T A G G A G
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Unit 8b­Modern Genetics
15. What holds the DNA base pairs together?
Hydrogen
Bonds
*Why is this important to the way DNA works?
Hydrogen bonds are easily separated and put back together, allowing DNA template to be copied and transcribed
16. DNA Replication:
a. What is DNA Replication?
make a
copy of DNA
b. What organic molecule
controls DNA replication?
enzymes
c.
Where and when does DNA replication occur?
Nucleus
Before cell division
d.
Why does a cell need to replicate its DNA before cell division?
Each cell gets the correct amount of DNA
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Unit 8b­Modern Genetics
e. How does DNA replication occur?
Step 1: DNA is unzipped­ Helicase
Step 2: Nucleotides are added to make a new DNA strand (DNA Polymerase)
Step 3: DNA is rezipped
AATGC
TTACG
AATGC
TTACG
1.Unzip
AATGC
TTACG
2.Base Pair
AATGC
TTACG
AATGC
AATGC
TTACG
AATGC
TTACG
AATGC
TTACG
3. Another
Replication
Proteins involved in DNA Replication DNA helicase Single­stranded binding proteins RNA primase
DNA polymerase
*Okazaki fragments DNA ligase https://www.youtube.com/watch?v=5qSrmeiWsuc
http://highered.mcgraw­
hill.com/sites/0072943696/student_view0/chapter3/animation__dna_replication__quiz_1_.html
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Unit 8b­Modern Genetics
Example: Language of Protein Synthesis
Step 1: Transcription
¡Que pase un buen día!
Step 2: Translation
¡Que pase un buen día!
Have a nice day!
DNA
RNA
PROTEIN
18. The Central Dogma of Genetics:
DNA
RNA
Transcription
PROTEIN
Translation
→ Traits
Expression
Protein synthesis
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Unit 8b­Modern Genetics
19. Transcription:
What is it?
DNA → mRNA
Where does it occur?
Nucleus
How does it occur?
Promoter­"start Here"
RNA Polymerase
adds RNA nucleotides
to new make mRNA strand
Terminator­''Stop
Here"
* Why is transcription necessary?
mRNA brings code from DNA in the nucleus to ribosome to be translated into proteins
Replication
Transcription
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Unit 8b­Modern Genetics
19. Translation:
What is it?
mRNA ­> Protein
Where does it occur?
Ribosome (cytoplasm)
How does it occur?
mRNA brings code to ribosome
tRNA brings a.a. to ribosome
Ribosome builds polypeptide by adding amino acids to the chain (peptide bonds)
What is a codon and an anticodon?
codon­ 3bp on the mRNA (code for an amino acid)
anticodon­ 3 bp on the tRNA that complements the codon
How does the ribosome know when to start and stop?
Start codon­ AUG (met)
Stop codons­ ex. UAA
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Unit 8b­Modern Genetics
20. How do we know which codon codes for which amino acid?
http://learn.genetics.utah.edu/content/molecules/transcribe/
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Unit 8b­Modern Genetics
21. Beadle and Tatum
Revised hypothesis:
1 Gene = 1 polypeptide
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Unit 8b­Modern Genetics
Specific Shapes = Specific Functions
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Unit 8b­Modern Genetics
AA sequence
• Random!
• Human genome has more than 3 billion base pairs(odds are that some mutations will occur)
• How? during Replication and transcription
• Sources of variation that cause evolution
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Unit 8b­Modern Genetics
Known causes: (mutagenic agents)
1. Radiation­ X­rays, uv light, cosmic rays
2. Carcinogens­ cancer causing chemicals
3. Certain drugs, pesticides (ex. DDT)
Depends on the mutation!
Silent mutations- don't occur in a "gene" or don't change the
genes expression (no effect)
Beneficial- if a mutation helps an organism survive better in its
environment, it will be passed on to more offspring (Natural
Selection!)
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Unit 8b­Modern Genetics
Harmful- occur on a gene or chromosome and change the expression of the gene(s)cause genetic disorders
-Harmful mutations in the body cell will only
affect individual
- Harmful mutation in the gametes can be
passed to offspring
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Unit 8b­Modern Genetics
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Unit 8b­Modern Genetics
homologous chromosomes or sister chromatids don't separate properly during cell division
Trisomy ­3 chromosomes (extra)
(Down syndrome)
Monosomy ­ 1 chromosome (missing)
(Turner's syndrome)
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