Cell Cycle Study Guide

Question 1

DNA is used to complete two two crucial cellular jobs. What are they?

Question 2

What are the two major phases of the cell cycle? Which one is longer?

Answer 2

Interphase (longer) and Mitosis

Question 3

What are the 3 subphases of Interphase? When is DNA replicated?

Answer 3

• G1(gap1): growth, protein synthesis, cell metabolism
• S(synthetic): DNA replication
• G2(gap2): preparation for division

Question 4

Regarding DNA replication, define replication fork, replication bubble, DNA polymerase, DNA ligase, nucleotides, and semiconservative replication

Answer 4

• replication fork: the point where the DNA strands separate
• replication bubble: area of active replication
• DNA polymerase: positions complementary free nucleotides to form new strands; only works in one direction
• DNA ligase: fuses lagging strand that is being synthesized discontinuously
• semiconservative replication: one complete DNA strand is given to a new cell and one is kept in the old cell
• nucleotides: (ATGC) forming pairs on DNA strand

Question 5

What types of cells perform mitosis efficiently? Which do not?

Answer 5

• Skin cells do mitosis efficiently
• nerve, skeletal, and cardiac cells do NOT

Question 6

What are the 4 steps of cellular mitosis? Be familiar with what cellular events are happening within each step. Be prepared to look at a picture and identify the stage of mitosis occurring.

Answer 6

• Prophase: chromatin condenses into chromosomes and mitotic spindle is formed, nucleolus disappears
• Metaphase: centromeres are aligned at metaphase plate (equator of spindle)
• Anaphase: shortest, centromeres split, cytokinesis begins (cleavage furrow)
• Telophase: chromosomes uncoil back into chromatin, nucleoli reappear, spindles disappear

Question 7

What is cytokinesis? When does it start? When is it completed?

Answer 7

The cell is splitting into two. Begins during late anaphase and ends in telophase.

Question 8

What can occur when cells ignore mitosis stop signals?

Answer 8

cells duplicate rapidly and can cause tumors or cancer

Question 9

What are proteins made of?

Answer 9

polypeptide chains that are made of amino acids

Question 10

Define a gene. Define a codon.

Answer 10

• gene: a segment of a DNA molecule that carries the code for creating 1 polypeptide chain
• codon: 3 sequential bases that code for a particular amino acid (ex ggc=proline)

Question 11

What is the role of RNA during protein synthesis?

Answer 11

• copies the DNA code and carries it through the cytoplasm to the ribosomes
• “go-between” molecule that links DNA to proteins

Question 12

What are the two steps to making proteins? What happens in each step? Which happens first?

Answer 12

1. transcription: DNA’s information is encoded in mRNA
2. Translation: information carried by mRNA is decoded and used to assemble polypeptides
   * dna -> RNA -> protein
   (C COMES BEFORE L)

Question 13

Define autophagy and apoptosis. Why would a cell practice autophagy? Or Apoptosis?

Answer 13

1. autophagy: “self eating” process when cells malfunction but can recycle their parts
   - disposal of unneeded proteins and organelles
   - cell cannibalization in times of extreme stress
   - cell restructuring during development
2. apoptosis: programmed cell death
   - caspases (enzyme) degrade cell
   - neatly destructs cancerous, infected, or old cells

Question 14

Be confident in what cell differentiation or specialization means and how it occurs!

Answer 14

cell differentiation: the development of specific and distinctive features in cells (making them different from each other)
- in the embryonic stage, chemical signals channel cells into the specific developmental pathways by turning genes on / off.

Question 15

Give an example of when hyperplasia might occur. How about atrophy?

Answer 15

• Hyperplasia: accelerated growth - increases cell numbers when needed (muscle growth)
• Atrophy: a decrease in size that results from loss of stimulation/lack of use (when you break a bone and the muscle shrinks)