lec 4 cell division

Question 1

Why is cell divison nessecary?

Answer 1

-growth+development
-maintain+replace tissue
-pass genetic info

Question 2

What are 2 broad stages of cell division? What happens?

Answer 2

Interphase: prepares cell for division
Mitosis OR miosis: cell divides

Question 3

Where does mitosis occur?

Answer 3

cells that make up body but not involved in sexual reproduction

(ex skin cells)

Question 4

Where does miosis occur?

Answer 4

cells that sexually reproduce

Question 5

What is mitosis? What must be replicated and passed onto the divided cells?

2 things

Answer 5

parent cell divides into 2 identical daughter cell

FIRST it replicates DNA+organelles, then divides

each daughter cell must have;
-full compliment of DNA from parent
-same organelles as parent

Question 6

What are the 3 major stages of interphase?

Answer 6

G1, S and G2

Question 7

What does each stage of interphase do? In order

Answer 7

G1: particular proteins made+activated for S phase

S (synthesis): DNA replicated

G2: makes proteins to prepare cell for mitosis

Question 8

Which of our cells are actively dividing?

Answer 8

Skin and intestinal

Question 9

What phase do liver cells remain in?

Answer 9

G0 or resting phase for up to a year before undergoing division

Question 10

What is a chromosome?

Answer 10

single strand of DNA

Question 11

How does DNA fit in the nucleus? What is this called?

Answer 11

tightly wrapped around proteins

DNA+protien= chromatin

Question 12

When is the only time we can see chromosomes fully?

Answer 12

When DNA fully packed, during mitosis

Question 13

What must chromosomes do for mitosis to occur?

Answer 13

Replicate

Question 14

How and when are chromosomes replicated?

how many phases

Answer 14

5 phases, before mitosis

Question 15

What is a chromatid? How are they joined?

Answer 15

each half of replicated chromosome

2 chromatids held together by centromere

(x shape, like chromosome, but a copy)

Question 16

What are the stages of mitosis?

Answer 16

Interphase, early prophase, late prophase, Anaphase, Telophase

Question 17

What occurs in each stage of mitosis?

Answer 17

Interphase: DNA replicated

Early Prophase:
-first stage
-DNA condensed
-centrosomes move to opposite poles

Late prophase:
-nuclear envelope dissolves,
-spindle fibers attach to chromosomes

Anaphase:
-DNA segregation
-chromatids separated into single, daughter chromosomes by fibers
(chromatids–> new chromosomes)
(x shape ripped apart into 2 sticks)

Telophase: chromosomes arrive at spindle poles

Cytokenisis: cell divides

Question 18

Why are centrosomes important?

Answer 18

spindle fibers (microtubules) grow outwards from centrosomes

Question 19

What do spindle fibers do? where do they attach? where do they bring chromosomes?

Answer 19

attatch to each chromosome, and to each pole

-attatchment occurs at protein in centromere called kinetochore

-then, line up (single line, theyre on top of each other) chromosomes on metaphase plate (central equator of cell) during metaphase

Question 20

What occurs in telophase, detailed.

Answer 20

Last stage of mitosis

-spindle fibers break down
-chromosomes less condensed
-nuclei start forming

Question 21

What is the process called when cells PHYSICALLY divide, what forms?

Answer 21

Cytokinesis

in animal cells, cleave-furrow forms
-cell is pinched more and more until divided

Question 22

What is another name for mitosis?

Answer 22

Nuclear division

Question 23

What is the difference between mitosis in animals vs in plants?

Answer 23

same as mitosis, but cells dont pinch off

-vesicles carry cell wall components to central equator

-fuse together to create cell plate, then form cell wall

Question 24

what are pairs of chromosomes called? How many do we have and where do they come from?

Answer 24

homolouges

23 pairs,

23 individual chromosomes from each father and mother

Question 25

what are human gamates? what is important about gamates? how are they produced?

Answer 25

egg and sperm gamates are HAPLOIDS, meaning they contain half of compliment of chromosomes produced by MEIOSIS by diploid germ cells

Question 26

what do diploid germ cells have? what do they do?

Answer 26

diploid= contains full compliment of chromosomes go thru meiosis to produce sperm (gamate) which is haploid

Question 27

what are haploids?

Answer 27

contain half of compliment of chromosomes gamates are haploids

Question 28

what is it called when two haploids fuse?

Answer 28

fertilization

Question 29

what is a zygote?

Answer 29

result of fertilization 2 haploids=full compliment of DNA in zygote

Question 30

how are gamates made?

Answer 30

first, halving # of chromosomes happens in meiosis 1

Question 31

what is meiosis 1 process of meiosis w/ respect to mitosis?

Answer 31

meiosis 1 same stages of mitosis, BUT each chromosome pairs with its homologue

Question 32

what is it called when a chromosome pairs w/ it's homologue to form a pair?

Answer 32

bivalent pair

Question 33

function of each phase in meiosos

Answer 33

prophase 1: chromosomes pair metaphase 1: spindle fibres attatch anaphase 1: each bivalent pair seperated, not chromosomes ripped apart telophase 1: nuclei with HALF the chromosomes

Question 34

what do spindle fibers do during meiosis

Answer 34

chromosomes line up in pairs spindle from each side connects to ONLY the pairs on their side

Question 35

essentially, what is meiosis?

Answer 35

halving the chromosome number

Question 36

what are the resulting daughter cells of meiosis considered as?

Answer 36

haploid

Question 37

what happens after meiosis 1? what happens in anaphase 2?

Answer 37

meiosis 2: similar to mitosis -haploid cells from meiosis 1 undergo second division -chromatids seperate at anaphase 2

Question 38

what is the result of meiosis 2?

Answer 38

4 haploid cells (gamates) w/ HALF the chromosome number - NOW X shape into 2 peices

Question 39

in very simple terms, what is a big difference b/w mitosis and meiosis

Answer 39

mitosis: chromosomes seperated into chromatids meiosis: chromosomes NOT seperated (2 FULL chromosomes paired up, then pairs seperated)

Question 40

very simply draw the dividing of chromosomes/pairs in mitosis and meiosis 1 and 2

Answer 40

MITOSIS X ---> I.......I X ---> I.......I X ---> I.......I X ---> I.......I MEIOSIS 1 XX --> X ..........X XX --> X ..........X MEIOSIS 2 X ......X ---> II......II X .......X --> II......II | (dots are just spaces)