Module 1-1

Question 0

Eukaryotic DNA Replication

Answer 0

Mitosis
- 2 identical daughter cells
Meiosis
- Reduces genetic material content and number of chromosomes by exactly one half
- Sexual reproduction

Question 1

Prokaryotic DNA Replication

Answer 1

Replicate DNA with each cell division but do not have nuclear membrane (nucleus)
Circular and make use of replication fork

Question 2

Nucleus

Answer 2

Membrane bound structure that holds genetic material

Question 3

Nucleolus

Answer 3

An amorphous component where ribosomal RNA is synthesized and where initial stages of ribosomal assembly occur

Question 4

Centrioles

Answer 4

Organize spindle fibers used in mitosis and meiosis

Question 5

Interphase

Answer 5

The initial stage of cell cycle

Genetic material is not visible

Question 6

G1 Stage

Answer 6

1st checkpoint for cells
Nondividing enter G0 stage
Dividing proceed to S stage

Question 7

S Stage

Answer 7

DNA replication

Question 8

G2 Stage

Answer 8

2nd checkpoint for cells
By the end, cell volume has doubled
Checks DNA replication

Question 9

Mitosis

Answer 9

Produces the two daughter cells

Genetic material visible

Question 10

Prophase

Answer 10

Takes up over half of time of mitosis
Centrioles divide and move apart
Chromosomes coil up and condense

Question 11

Prometaphase

Answer 11

Can clearly see double structured chromosomes

Centrioles reach opposite poles and spindle fibers form

Question 12

Metaphase

Answer 12

Centromeres align on metaphase plate

Question 13

Anaphase

Answer 13

Centromeres split and daughter chromosomes move to opposite poles

Question 14

Telophase

Answer 14

Daughter chromosomes arrive at poles and cytokinesis begins

Question 15

Sister chromatids

Answer 15

Two identical parts of chromosomes

Question 16

Diploids

Answer 16

Chromosomes are homologous pairs

Types depend on position of Centromeres

Question 17

Centromeres in middle

Answer 17

Metacentric

Question 18

Centromeres between middle and end

Answer 18

Submetacentric

Question 19

Centromeres close to end

Answer 19

Acrocentric

Question 20

Centromeres at end

Answer 20

Telocentric

Question 21

Karyotype

Answer 21

Photograph of squash of chromosomes

Taken at Metaphase when sister chromatids are still attached to one another (following DNA synthesis)

Question 22

Quantifying Genetic Material

Answer 22

N = number of chromosomes in a haploid set
ex: human sperm cell = N = haploid = 23
2N = diploid, ex: human liver cell is 2N = 46
C = amount of DNA (weight) in an N nucleus
ex: human C = 0.3pg, frog C = 3pg (pg = 10^-12 grams)

Question 23

DNA base pairs

Answer 23

Humans: 3*10^9 base pairs, 20000-25000 genes

Question 24

Mitosis

Answer 24

Occurs in embryo and during organ development
In adults in renewable tissues (stem cells)
-epidermis, GI tract, mammary glands, lung, blood forming tissue, testis and ovary, liver

Question 25

Kinetochores and Centromeres

Answer 25

• Centromeric DNA is specific DNA (tandem repeating sequences) that facilitate the binding by centromeric proteins
• Kinetochore proteins bind to centromeric proteins
• Allows attachment to spindle fibers, made up of alpha, beta, and gamma tubulin, which facilitates transport to poles

Question 26

Cell cycle checkpoints

Answer 26

Specific times during cell cycle where damage to cell is assessed prior to mitosis

• prevents damaged cells from replicating
  
  • Damaged cells move towards Apoptosis- Cell Death

Question 27

G1/S

Answer 27

Checks for DNA damage

Monitors the size of the cell and evaluates condition of DNA

Question 28

S

Answer 28

Checks for incomplete DNA synthesis

Question 29

G2/M

Answer 29

Checks for DNA damage

Checks if DNA replication is incomplete

Question 30

M

Answer 30

Checks for incomplete spindle formation

Checks for attachment of spindle fibers to the kinetochores associated with the centromeres

Question 31

Cell Division Cycle Mutations

Answer 31

The checkpoints in the cell cycle act as decision process for proceeding to division
Many of the mutated genes are enzymes called Kinases that add phosphates to other proteins
Function in conjunction with proteins called cyclins (Cyclin Dependent Kinases (CDK))
Post-Translational modification of a protein

Question 32

Kinase Enzymes

Answer 32

Modify other proteins by phosphorylating them
Addition of phosphate can change target protein’s localization, activity, or association with other proteins
Kinases are involved in cell signaling pathways and cell division pathways
Mutated kinases associated with disease phenotypes including cancer

Question 33

Kinase activation segment

Answer 33

Domain frequently shown to harbor oncogenic mutations in known kinase cancer genes

Question 34

P-Loop

Answer 34

conserved structural region of kinases involved in ATP-binding

Question 35

Cyclin Proteins

Answer 35

Cyclin levels vary during cell cycle
Levels of activated kinase complexes vary throughout the cell cycle
Causes variable phosphorylation by kinases and different results/effects depending on point in cell cycle

Question 36

Cell Division Mutations

Answer 36

Different mutations operate at various checkpoints of cell cycle
Ex: p53 recognizes damaged DNA at G1/S checkpoint and targets cell for apoptosis
-Therefore p53 is a tumor-suppressor gene

Question 37

p53 Tumor Suppressor Gene

Answer 37

Found in inactivated and activated form
Normally inactivated form predominates
Events that lead to increase in active form: chemical damage to DNA, dsDNA breaks, UV light damage…
Activation of p53 is caused by phosphorylation and acetylation
Activated p53 is a DNA tf that turns on other genes
Initiates 2 responses to DNA damage
1. Arrest of cell cycle followed by DNA repair
or
2. Apoptosis and Cell death
Can act in other points in cell cycle: S, G2/M
Cells lacking in p53 = malignant cells
p53: “Guardian of the Genome”