test 2: lecture 8 - cell division & dna replication

Question 1

somatic cells go through which process? mitosis or meiosis?

Answer 1

mitosis (ex: skin cells) - more common

Question 2

sexual cells go through which process? mitosis or meiosis?

Answer 2

meiosis (ex: eggs, sperm)

Question 3

who discovered DNA?

Answer 3

waston, crick and franklin

Question 4

what is always the first step of mitosis or meiosis?

Answer 4

DNA replication

Question 5

DNA replication

Answer 5

• DNA unzips and gets copied
• happens in nucleus
• result: 2 identical copies of DNA
• replication is semiconservative: 1 parent strand + 1 new strand

Question 6

semiconservative model

Answer 6

two strands of the parental molecule seperate and each functions as a template for synthesis of a new, complementary strand

Question 7

base pairing in DNA

Answer 7

adenine - thymine

guanine - cytosine

Question 8

what does DNA copying start with?

Answer 8

RNA primer

Question 9

in which direction does replication occur?

Answer 9

5’ to 3’ (nucleotides added onto 3’ end)

Question 10

what enzyme helps DNA replication?

Answer 10

DNA polymerase

Question 11

what is the mechanism that checks for & corrects mistakes?

Answer 11

mismatch repair

Question 12

what are the 4 noncoding DNA sequences?

Answer 12

• transcription/translation regulators
• origins of DNA replication
• centromeres
• telomeres

Question 13

what are telomeres?

Answer 13

special noncoding sequences added onto the end of eukaryotic chromosomes to protect them from being eroded

Question 14

true or false? when eukaryotic cells divide, chromosomes get shorter

Answer 14

true - ends of chromosomes do not get fully replicated

Question 15

facts about telomeres

Answer 15

• do not contain genes
• provide protective function by postponing erosion of genes located near ends of DNA molecules
• shrink every time cell divides
• proposed that shortening telomeres is connected to the aging process

Question 16

what is the name of the special enzyme germ cells have and what does it do?

Answer 16

telomerase - catalyzes the lengthening of telomeres in eukaryotic germ cells

Question 17

cell cycle

Answer 17

G1, S, G2, mitosis

Question 18

what is interphase?

Answer 18

G1, S, G2

Question 19

what is the shortest phase of the cell cycle?

Answer 19

mitosis

Question 20

what happens during G1 and G2?

Answer 20

cells grows and makes proteins, organelles

Question 21

what happens during S phase?

Answer 21

only DNA replication going on

Question 22

G1 phase:

Answer 22

• beginning of cell’s life
• centrioles divide
• cytokinesis
• cell grows to full size
• transcription and translation occur
• DNA in single strands

Question 23

what causes the area around centrioles to be thicker than rest of cytoplasm? what is this called?

Answer 23

it’s called the centrosome - the helper proteins used by centrioles to help make spindle fibers cause this area to be thicker

Question 24

S phase:

Answer 24

• DNA replicates - 2 double stranded DNA molecules
• diploid and haploid
• no more RNA (leftovers used for repairs)
• centrosomes, centrioles still replicating
• WITHOUT THIS PHASE CELLS CANT DIVIDE

Question 25

G2 phase:

Answer 25

- well defined nucleus with membrane - centrosomes present, centriole copying complete - DNA has duplicated, but it in chromatin form - RNA transcribed to make proteins (spindle fibers) - leftover RNA used for repairs

Question 26

which is the most important permission point of the cell cycle?

Answer 26

G1 checkpoint

Question 27

centrosome

Answer 27

area for production and organization of microtubules

Question 28

true or false? plant has centrioles

Answer 28

FALSE - plant has centrosome, but no centrioles

Question 29

explain how centrioles and centrosome act in animal cells

Answer 29

centrioles replicate centrosome divides --- result: two centrosomes (each with a pair of centrioles), move to opposite ends of nucleus, microtubules grow into spindle from each centrosome

Question 30

what are spindle fibers responsible for?

Answer 30

seperating the dividing cell and contents into new cell

Question 31

nerve and muscles cells are always in which phase?

Answer 31

G0

Question 32

liver cells are in which phase?

Answer 32

G0, but can be activated to come out of it

Question 33

true or false? cancerous cells obey checkpoint control

Answer 33

false

Question 34

what are check points controlled by?

Answer 34

regulatory protein - p53

Question 35

what is p53?

Answer 35

most important regulatory protein, classified as a tumor suppressor protein

Question 36

how does p53 fight cancer?

Answer 36

1- pause cell cycle and initiate DNA repair | 2- if DNA cannot be repaired, it will induce apoptosis

Question 37

apoptosis

Answer 37

programmed cell death

Question 38

how can cells lead to cancer?

Answer 38

if a damaged cell does not undergo apoptosis and divides