Lecture 10

Question 1

Bacterial cell division called

Answer 1

Binary fission

Question 2

Cell cycle

Answer 2

Grow and replicate DNa> divide , repeat

Question 3

Cell division in a nutshell

Answer 3

Replicate DNA then divide

Question 4

Eukaryotic cell cycle

Answer 4

Grow> replicate DNA> grow some more> divide

Repeat

Question 5

Interphase stages

Answer 5

G1- cell grows and prepares for S phase (G stands for Gap”

S- synthesis of DNA. DNA replicated to make a complete copy

G2- cell grows and prepares for mitosis

Question 6

G1

Answer 6

Cell grows and prepares for S phase

G stands for gap

Interphase stage

Question 7

S stage interphase

Answer 7

Synthesis of DNA. DNA replicated to make a complete copy

Question 8

G2 interphase

Answer 8

Cell grows and prepares for mitosis

Question 9

G0 aka G naught

Answer 9

Resting state. Not actively dividing or preparing to divide

Question 10

Prokaryotic cell cycle

Answer 10

Single circular chromosome is pulled apart during replication

During cytokinesis, membrane constricts and new cell wall is formed between daughters

Very fast (as little as 10 minutes), so the stages basically overlap instead of being separated over time like in eukaryotes

Question 11

Replication of eukaryotic chromosomes create what

Answer 11

2 sister chromatids

Question 12

Centromères

Answer 12

Hold together chromosomes and chromatids at the center

Question 13

Haploid vs diploid

Answer 13

1 set of DNA ( purple)

Vs

1 set of homologous chromosomes. 1 from mom (red) and 1 from dad (blue)

Question 14

Mitosis phases

Answer 14

Prophase

Prometaphase

Metaphase

Anaphase

Telophase

Cytokinesis

Question 15

Prophases

Answer 15

Chromosomes condense and become visible

Nuclear envelope begins to break down

Spindle starts to form

Question 16

Prometaphase

Answer 16

Nuclear envelope breaks down

Chromosomes attach to microtubules and moved to mid zone

Question 17

Metaphase

Answer 17

Chromosomes attached to microtubules and align at the metaphase plate

Question 18

Anaphase

Answer 18

Sister chromatids separate and move to opposite poles of the cell

“Aaaaaaahhhh naphase. Ripping apart”

Question 19

Telophase

Answer 19

Chromosomes decondense

Nuclear envelope reforms around daughter nuclei

Spindle fibers disappear

Question 20

Cytokinesis

Answer 20

Division of the cytoplasm. Typically begins during late anaphase or telophase. Resulting in 2 daughter cells

Question 21

Nucleosome

Answer 21

A protein complex consisting of histone proteins that DNA wraps around

Question 22

Microtubules in the animal spindle

Answer 22

Kinetochore microtubules- move chromosomes around

Non-kinetochore- hold spindle together and control its length

Astral microtubules- spindle positioning and length control

Question 23

Where at the spindles Positive and negative?

Answer 23

+ in equator

• at the poles

Question 24

Kinetochore microtubules attach to what

Answer 24

Kinetochore of each sister chromatid

Question 25

Centromere

Answer 25

Constricted region of chromosome linking sister chromatids

Question 26

Kinetochore

Answer 26

Complex of proteins

Question 27

2 mechanisms of anaphase

Answer 27

Anaphase A: kinetochore MTs shorten (chromatids move to poles) Anaphase B: non Kinetochore MTs slide apart (spindle elongates)

Question 28

Mechanism of poleward chromosome movement during anaphase

Answer 28

Microtubules motor protein “walks” along microtubules and it disassembles as the Kinetochore passes over it

Question 29

Mitosis things to pay attention to. To determine what phase

Answer 29

Chromatin: condensed or not? Nuclear envelope: present or not? Centrosomeres(animals): replicated? Position? Chromosomes: position? Attachment to microtubules? Sister chromatids attached?

Question 30

Cell cycle / mitosis

Answer 30

Interphase G1 Interphase G2 Prophase Prometaphase Metaphase Anaphase Telophase+ cytokinesis Repeat

Question 31

Cytokinesis in animal cells

Answer 31

Cleavage furrow forms as the contractile ring pulls membrane in like a drawstring until it eventually pinches the 2 cells apart Contractile ring consists of microfilaments

Question 32

Prophase summary

Answer 32

DNA condensed Nuclear envelope begins to break down Centrosomes (animal cells) duplicated and migrating to poles

Question 33

Prometaphase summary

Answer 33

Nuclear envelope gone MTs “search and capture” chromosomal kinetochores Move them towards spindle midzone Centrosomes migrating to create 2 poles

Question 34

Metaphase summary

Answer 34

Replicated chromosomes are attached to MTs Aligned at metaphase plate Spindle is bipolar

Question 35

Anaphase summary

Answer 35

Sister chromatids separate Pulled towards poles (as Kinetochore fibers shorten) Spindle elongates (as Kinetochore MTs slide apart)

Question 36

Telophase summary

Answer 36

Nuclear division (karyokinesis) is complete Spindle disassembles Chromosomes decondense Nuclear envelope reforms in each daughter cell

Question 37

Cytokinesis summary

Answer 37

Overlaps with telophase / late anaphase Ends when daughter cell completely separated (each having own plasma membrane and cytoplasm)

Question 38

Mitotic spindle in plants

Answer 38

No centrosomes, so spindles tend to be broader at poles “Acentrosomal spindles”

Question 39

Cytokinesis animals vs plants

Answer 39

Animal divides out to in (Luke a rubber band around it) Plant divides in to out: cell plate starts growing in the middle and cuts across

Question 40

Sexual reproduction

Answer 40

-produces genetic variation which is the basis for evolution Genetic diversity in a population allows adaptation to changes in environment Meiosis is the source of this genetic variation

Question 41

Meiosis purpose

Answer 41

Generate genetic variability by shuffling DNA Creates egg and sperm (gametes) Gametes only have one copy of each chromosome (haploid)

Question 42

Diploid life cycle

Answer 42

1n > fertilization > 2n > meiosis Repeat

Question 43

Diploid life cycle in most animals

Answer 43

Meiosis> gametes 1n > fertilization > zygote 2n > mature 2n > meiosis Repeat

Question 44

Meiosis vs mitosis

Answer 44

Mitosis: 2n > creates 2 2n cells Meiosis: 2n > 2 1n cells > each producing 2 1n (4total)

Question 45

Naming convention for chromosome numbers Haploid vs diploid numbers

Answer 45

1 chromosome: *1 haploid number (1n) * 2 diploid number (2n) 2 chromosome: * 2 haploid number (1n) * 4 diploid number (2n) And so on

Question 46

How does meiosis increase genetic diversity

Answer 46

By mixing/ recombining chromosomes