Download Unit 5 : Cell Growth and Reproduction

Unit 5 : Cell Growth and
Reproduction
Lesson 1: Genes and Proteins
Synthesis
Objectives:
• Genes and Protein Synthesis
• The Cell Cycle, DNA Replication, and Mitosis
• Genes, Alleles, and Meiosis
DNA
• Deoxyribonucleic acid
• Blueprint for building proteins.
• Monomers: nucleotides (sugar, base,
phosphate group)
Bases
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Bases of DNA are:
Adenine (A)
Cytosine (C)
Guanine (G)
Thymine (T)
DNA is a double stranded molecule.
Adenine bonds with Thymine
Cytosine bonds with Guanine
Codons
• Group of three nucleotides is called a codon.
• The sequence of nucleotides determines what
amino acid will be added to make a protein.
• A region of DNA that codes for a protein is a
gene.
• *Remember the monomer of protein is an
amino acid.
• Gene expression: The process by which
genetic information is used to make a protein.
Chromosomes
• DNA winds around proteins called histones,
which coil and condense to make
chromosomes.
• Prokaryotes have DNA that winds into a circle.
One strand of DNA contains the base
sequence ACGGTATCG.
What base sequence does the complementary
strand contain?
a. CTAAGCGTA
b. ACGGTATCG
c. TGCCATAGC
d. GCTATGGCA
Transcription
• DNA is copied and a “transcript” of the
information moves out of the nucleus into the
cytoplasm in order to be read to make a
protein.
• The “transcript” (or copy of DNA) is called
RNA.
• RNA is only single stranded and has Uracil
instead of Thymine.
Transcription cont.
• RNA (ribonucleic acid)
• Transcription : process when DNA is copied into a
strand of mRNA. (messenger RNA)
• Steps to Transcription:
• 1. protein separates the two strands of DNA.
• 2. One strand of DNA is transcribed into mRNA.
• 3. RNA polymerase (protein) attaches the correct
RNA nucleotide to build the strand of mRNA.
Transcription video
• https://www.youtube.com/watch?v=ztPkv7wc
3yU
Translation
• There are 20 different amino acids that make
up proteins.
• The order of amino acids in a protein
determines the protein’s 3-d structure and
function.
• Translation: process of making proteins from
mRNA.
• Proteins are made in the cytoplasm on a
ribosome.
Translation cont.
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Ribosomes contain rRNA (ribosomal RNA) and protein.
Steps to Translation:
1. mRNA attaches to a ribosome.
2. The ribosome reads the mRNA and tRNA (transfer
RNA) will transfer the correct amino acid onto the
chain to build a protein.
• 3. The anticodon is the region on tRNA that is
complementary to the codon found on the mRNA.
• Ex. UGG is the codon for the amino acid tryptophan. A
tRNA molecule that binds to tryptophan has the
complementary anticodon sequence ACC.
Translation cont.
• There are “start” codons and “stop” codons
that helps the tRNA determine where to start
building a protein and where to stop.
Translation video
• https://www.youtube.com/watch?v=zb6r1MMTkc
Question
Amino Acid
Serine
Valine
Leucine
Anticodon
AGA
CAA
GAU
What mRNA sequence was used to make a
polypetide strand of serine, valine, and leucine?
Protein Synthesis in the Cell
• Proteins are made on ribosomes.
• Ribosomes are either attached to the ER or are
free floating in the cytoplasm.
• If the protein is being made for the plasma
membrane they will be made on the rER.
• If protein is being made for the cell to use they
will be made on free ribosomes.
• The protein made on rER will be packed into
vesicles.
• These vesicles will travel to the Golgi Apparatus,
then will be modified and sent to the cell
membrane.
Question
• Which organelle is not involved in the
synthesis and secretion of a protein from the
cell?
• A. Ribosome
• B. Smooth ER
• C. Golgi apparatus
• D. Plasma membrane
Keystone Packet
• Complete ques. 1-6
• Pg. 112 & 113
Lesson 2: The Cell Cycle, DNA
Replication, and Mitosis
• Cell cycle: the life cycle of a cell.
3 main stages:
1. Interphase – G1, S, G2 (growth, DNA
replication)
2. Mitosis – nuclear division
3. Cytokinesis – splitting of the cytoplasm
DNA Replication
• Produces an identical copy of each
chromosome arm.
• Sister chromatid – each arm of a chromosome
• Centromere – center of chromosome that
holds the two sister chromatids together.
DNA Replication
• During the S phase of Interphase the DNA
replicates so that each daughter cell has a full set
of DNA.
Steps:
1. DNA helicase separates the two strands of DNA
2. DNA polymerase pairs up new nucleotides to
each side of the DNA.
Each new double strand contains one strand that
came from the original DNA and one newly made.
DNA replication video
• https://www.youtube.com/watch?v=dKubyIRi
N84
Mitosis
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Prophase:
The nuclear membrane breaks down
DNA coils up
Centrioles begin to move toward the poles of
cell
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Metaphase:
Centrioles produce spindles
Spindles attach to the centromeres
The chromatids line up along the center of the
cell.
• Anaphase:
• Spindles shorten
• The chromatids pull apart and move toward
opposite poles of the cell.
• Telophase:
• Nuclear membrane reforms
• The chromosomes unwind and become longer
and thinner.
• Cytoplasm pinches
Cytokinesis
• Cell membrane pinches in center and two cells
are formed.
homework
• Pg. 120,121 – Keystone Packet Lesson 2
• Ques: 1-4
Crash Course – DNA Replication
https://www.youtube.com/watch?v=8kK2zwjRV
0M
Lesson 3 – Genes, Alleles, and Meiosis
• Review: mitosis – process in which the body
grows and repairs itself.
• Meiosis – occurs in organisms that reproduce
sexually, produces gametes (sex cells: sperm
or egg cells).
• Chromosomes: coiled up DNA, humans have
46 chromosomes (23 pairs)
Homologous chromosomes
• Your chromosomes are grouped as
homologous pairs.
• You have one side of the pair from your mom
and the other from your dad.
Allele
• On each location there is a gene but different
versions of the gene on each chromosome.
• Allele – version of “flavor” of a gene.
• In your body cells you have two alleles for
each gene.
• In sex cells you have only one allele for each
gene.
Sex cells
• Sex cells contain half the set of chromosomes.
• They are called haploid cells – half the set of
chromosomes. n
• Diploid cells – contain the full set of
chromosomes. 2n
• n = 23 pairs
• 2n = 2(23) = 46 chromosomes.
Meiosis
• Before Meiosis starts the cell has gone
through interphase.
• During interphase the DNA is duplicated so
the cell has two sets of 23 pairs.
• Two divisions to Meiosis:
– Meiosis I – one cell divides into two cells. Each cell
is 2n.
– Meiosis II – two cells divide into four cells. Each
cell is n.
Meiosis I
• Crossing –over : this occurs
during Meiosis I.
• The homologous pairs cross
their chromatids and
exchange DNA.
• This occurs so that the egg
or sperm cells are
genetically diverse.
Phases of Meiosis
Prophase I – the nuclear membrane breaks down.
Chromosomes coil.
Crossing-over occurs
Metaphase I
- Chromosomes line up in middle.
- Chromosomes are in pairs called tetrads.
- Spindle fibers attach to centromeres.
• Anaphase I
• - spindles shorten
• The pairs of homologous chromosomes
separate.
• Telophase I
• Nuclear membrane reforms.
• Then cytokinesis occurs and end result is two
2n cells (diploid).
• Prophase II
• The chromosomes condense again.
• New spindles form
• Metaphase II
• The chromosomes line up in middle of cell.
• Spindle fibers attach to centromere.
• Anaphase II
• Spindles shorten.
• Sister chromatids separate (just like in
mitosis).
• Telophase II
• Chromosomes uncoil.
• Nuclear membrane reforms.
• End result: 4 haploid (n) cells. Genetically
diverse.
Differences between Mitosis and
Meiosis