Exam 3

Question 1

Identify the enzyme responsible for synthesizing mRNA

Answer 1

RNA polymerase

Question 2

Explain the differences between pre-mRNA and mature mRNA

Answer 2

Pre-mRNA is identical transcript produced during transcription
Mature mRNA is the processed version that is ready for translation

Question 3

Explain how cells with identical genomes can have different functions and identities

Answer 3

Cells become specialized through differential gene expression controlled by transcription factors,

Question 4

Describe how information in mRNA is used to make a polypeptide

Answer 4

Translation (starting, ribosomes assemble around the mRNA start codon. Rib zone has three sites a site. tRNA arrives peace sites growing polypeptide sites empties tRNA.)
Elongation- amino acid added peptide chain grows
Termination-stop put on reached polypeptide released

Question 5

Describe the roles of mRNA and tRNA in translation

Answer 5

mRNA- Carries the genetic instructions, Contains codons, Determines the amino acid sequence provides the instructions for protein synthesis
tRNA- Delivers the correct amino acids, Contains an anticodon, Ensures proper protein assembly ** brings the correct amino acid to the ribosome**

Question 6

Classify substitution (point) mutations as silent, missense, and nonsense and predict the consequence of each

Answer 6

Silent – no amino acid chain, protein remains functional, no effect
Missense – changes one amino acid, protein may be functional or defective, varies
Nonsense – changes to a stop code on shortened nonfunctional, protein, often severe

Question 7

Predict how insertions and deletions change the reading frame

Answer 7

Frameshift – ads/delete one or two bases, completely different amino acid, or early stop codon, severe
In frame ads or deletes, three bases or multiples of three, missing an extra amino acid, less severe, but still harmful

Question 8

Explain the significance of mutation to evolution

Answer 8

It introduces, genetic diversity
Enables adaptation to changing environments
It drives the formation of new species

Question 9

Understand that most mutations are neutral, and some are deleterious or beneficial

Answer 9

Neutral – no effect on fitness
Deleterious – decreased fitness
Beneficial – increases fitness

Question 10

Describe why cells divide

Answer 10

Growth (mitosis)
Repair and replacement (mitosis)
Asexual reproduction (mitosis/binary fission)
Sexual reproduction (meiosis)
Maintaining cell size (mitosis)

Question 11

binary fission

Answer 11

Who- prokaryotic (bacteria)
Why- asexual reproduction
Number of divisions – 1
Number of cells produced – 2
Genetic variations- no (identical cells)
Pilate of daughter cells – same as parent (haploid)

Question 12

Mitosis

Answer 12

Who- eukaryotic (animal, plants)
Why- growth repair asexual reproduction
Number of divisions – 1
Number of cells produced – 2
Genetic variations- no (identical cells)
Pilate of daughter cells – same as parent (diploid)

Question 13

Meiosis

Answer 13

Who- eukaryotic (organisms that reproduce sexually)
Why- sexual reproduction (gamete production)
Number of divisions – 2
Number of cells produced – 4
Genetic variations- yes (genetically unique cells)
Pilate of daughter cells – half a parent (haploid)

Question 14

Cell cycle

Answer 14

Interphase- G1, S, G2
M phase- mitosis, cytokines

Question 15

G1

Answer 15

Events- Cells grow British proteins and organelles
Outcome- Prepares for DNA replication
Chromosomes – 46
DNA molecules – 46

Question 16

S

Answer 16

Event – DNA replication
Outcome- chromatids form
Chromosomes – 46
DNA molecules – 92

Question 17

G2

Answer 17

Event – cells prepare for my mitosis
Outcome- ensures DNA is error free
Chromosomes – 46
DNA molecules – 92

Question 18

Prophase (mitosis)

Answer 18

Event – Gromo Ooms, condense, spindle form
Outcome – prepares for chromosome alignment
Chromosomes– 46
Metal DNA molecules – 92

Question 19

Prometaphase (mitosis)

Answer 19

Event- spindle fibers attached to kinetochores
Outcome – chromosomes move towards center

Question 20

Metaphase (mitosis)

Answer 20

Event – chromosomes align at metaphase plate
Outcome – ensures equal separation
Chromosomes – 46
DNA molecules – 92

Question 21

Anaphase (mitosis)

Answer 21

Event – sister chromatids separate
Outcome – moves chromatids to opposite poles
Chromosomes – 92
DNA molecules – 92

Question 22

Telophase (mitosis)

Answer 22

Event – nuclear envelopes, reform, chromosomes relax
Outcome – Prepares for cytokinesis
Chromosomes – 92
DNA molecules – 92

Question 23

Cytokinesis

Answer 23

Event – cytoplasm divides
Outcome – two identical daughter cells form
Chromosomes – 46
DNA molecules – 46

Question 25

G1 check point

Answer 25

Checks for DNA damage Sufficient cell size Adequate energy and nutrients Proper external signals (growth factors)

Question 26

G2 checkpoint

Answer 26

Check for Proper DNA replication (no mutations or errors) Sufficient cell size Proper organelle duplication

Question 27

M Checkpoint

Answer 27

Check for Proper chromosome alignment at the metaphase plate Correct attachment of spindle fibers to kinetochores

Question 28

p53

Answer 28

p53 is a crucial tumor suppressor gene that stops the cycle when DNA is damaged.

Question 29

Tumor Suppressor Genes

Answer 29

Function: Slow down cell division, repair DNA damage, or trigger apoptosis (programmed cell death). Normal Role: Prevent uncontrolled cell growth.

Question 30

Proto-Oncogenes (“Gas Pedal of the Cell Cycle”)

Answer 30

Function: Promote normal cell growth and division when needed. Normal Role: Respond to signals for growth and repair.