Cell Division

Question 1

What are the 2 main stages of the cell cycle?

Answer 1

interphase

mitotic

Question 2

What happens during interphase?

5 things

Answer 2

DNA replicated + checked for errors
Protein synthesis in the cytoplasm
Mitochondria grow + divide
Chloroplasts grow + divide
metabolic processes

Question 3

There are 3 stages of interphase, what are they called?

Answer 3

G1
S
G2

Question 4

What happens in the G1 stage of interphase?

Answer 4

Proteins are synthesised
organelles replicate
cell increases in size

Question 5

What happens in the S phase of interphase?

Answer 5

DNA is replicated in the nucleus

Question 6

What happens in the G2 stage of interphase?

Answer 6

cell increases in size

the replicated DNA is checked for errors

Question 7

What 2 stags are involved in the mitotic phases of the cell cycle?

Answer 7

mitosis

cytokinesis

Question 8

What happens in the G0 stage of the mitotic phase?

Answer 8

the cell leaves the cycle permanently/temporarily

Question 9

What are the reasons for going into the G0 stage?

Answer 9

differentiation- cell becomes specialised so can no longer divide
DNA may be damaged
Growing numbers of senescent cells

Question 10

G1 checkpoint is at the end of the G1 stage before the S phase, what is the purpose of this checkpoint?

Answer 10

if the cell satisfies requirements it triggers DNA replication

Question 11

G2 checkpoint is at the end of the G2 stage before the Mitotic phase, what is the purpose of this checkpoint?

Answer 11

checked for DNA without errors, if satisfies the requirements it initiates the being of mitosis

Question 12

Describe the cells that mitosis create?

Answer 12

2 daughter cells produced by a parent cell would be genetically identical, each will have the exact same copy of DNA

Question 13

What are 2 identical DNA molecules called?

Answer 13

chromatids

Question 14

What is the region called where the 2 chromatids joined together?

Answer 14

centromere

Question 15

What is the order of Mitosis?

Answer 15

prophase
metaphase
anaphase
telophase

Question 16

What happens in prophase?

Answer 16

chromatic fibre coil and condense, which form
chromosomes

the nucleus disappears

the nuclear membrane breaks down

spindle fibres link the 2 poles of the cell

spindle fibres attach to specific areas on the centromere

nuclear envelope disappears

Question 17

What happens in Metaphase?

Answer 17

chromosomes are moved by the spindle fibres to form the metaphase plate

Question 18

What happens in anaphase?

Answer 18

the centromeres holding the pairs of chromatids divide

The chromatids are separated and pulled to the opposite poles of the cell by the shortening of the spindle fibres.

Question 19

What happens in Telophase?

Answer 19

2 new chromosomes assemble and the nuclear envelope reforms

chromosome uncoil and the the nucleolus is formed

cytokinesis begins

Question 20

During cytokinesis in animals cells a cleavage furrow is formed around the middle, what causes this?

Answer 20

the cell surface membrane of the animal cell gets pulled in by the cytoskeleton

Question 21

Why can’t plant cells form cleavage furrows?

Answer 21

because they have cell walls

Question 22

What are the 2 sex cells called?

Answer 22

Gametes

Question 23

What is a fertilised egg called?

Answer 23

zygote

Question 24

Diploid

Answer 24

2 chromosomes inherited form each parent

Question 25

haploid

Answer 25

daughter cells that contain 1/2 the chromosomes number of the parent

Question 26

How many daughter cells are produced in meiosis ?

Answer 26

4

Question 27

What is a Homologous chromosome?

Answer 27

matching sets of chromosomes | diploid

Question 28

define Alleles

Answer 28

different variations of the same genes

Question 29

What happens in Meiosis 1 prophase 1?

Answer 29

chromosomes condense nuclear envelope disintegrates nucleolus disappears spindle fibres formation begins Homologous chromosomes pair up and form bivalents

Question 30

What happens in meiosis 1 metaphase 1?

Answer 30

same as mitosis 1 but the pairs of homologous chromosomes line up at the metaphase plate The orientation is random random assortment, resulting in different combination of alleles

Question 31

What happens in meiosis 1 anaphase 1?

Answer 31

Homologous chromosomes are pulled to opposite poles, the chromatids stay together Crossing cover occurs chiasmata - chromatids break and rejoin = recombinant chromatids

Question 32

What happens in meiosis 1 telophase 1?

Answer 32

chromosome assemble at each pole nuclear membrane reforms chromosomes un coil undergoes cytokinesis Diploid -----> haploid

Question 33

What shape are erythrocytes? | And why?

Answer 33

biconcave increased SA:V more space for haemoglobin don't have a nucleus so more space for haemoglobin

Question 34

What are the adaptations of neutrophils?

Answer 34

multi lobed nucleus - easier to fit into small gaps | granular cytoplasm - contains lysosomes to attack pathogens

Question 35

What are the adaptations of sperm cells?

Answer 35

Flagellum- enable movement Many mitochondria to supply energy The acrosome on the head of the sperm contains enzymes

Question 36

What are the Adaptations of palisade cells?

Answer 36

contain chloroplasts to absorb light rectangle shape to form a continuose layer Thin cell walls - shorter diffusion distances large vacuole to maintain turgor pressure

Question 37

What are the adaptations of root hair cells?

Answer 37

long extensions that increase SA:V ----> maximises the uptake of water+ minerlas

Question 38

What are the adaptations of guard cells?

Answer 38

small openings = stomata | sides are asymmetrical to open and close stomata

Question 39

Adaptations of squamous epithelium

Answer 39

made of flat cells, only 1 cells thick | present where rapid diffusion is needed

Question 40

Adaptations of ciliated epithelaim

Answer 40

have Cilla on the surface on 1 side beat rhythmically-----> mucus can be swapped away goblet cells are present

Question 41

Adaptations of cartilage

Answer 41

connective tissue contains elastin contains collegen made from chondrocyte cells

Question 42

Adaptations of muscle tissue

Answer 42

contain myofibrils | able to shorten and contact

Question 43

Adaptations of epidermis

Answer 43

single layer of closely packed cells covered by a cuticle | have stomata

Question 44

Adaptations of xylem tissue

Answer 44

vascular tissue transport of water and minerals elongated hollow dead cells lignified

Question 45

Adaptations of phloem tissue

Answer 45

transport of nutrients collum of sieve tubes have bordered pits

Question 46

What are undifferentiated cells called?

Answer 46

stem cells

Question 47

What are the 3 types of stem cell potency

Answer 47

totipotent pluripotent multipotent

Question 48

define totipotent

Answer 48

can differentiate into any type of cell

Question 49

define pluripotent

Answer 49

can form all tissue types but not whole organisms

Question 50

define multipotent

Answer 50

stem cells that can only form a range of cells within a curating type of tissue

Question 51

Where can you find plant stem cells?

Answer 51

meristematic tissue | vascular cambium

Question 52

Where can you find Animal stem cells?

Answer 52

embryonic stem cells = early stages of embryo developemt umbilical chords bone marrow

Question 53

What happens in meiosis 2 prophase 2?

Answer 53

chromosomes condense nucleus envelope breaks doen spindle fibre formation begins

Question 54

What happens in meiosis 2 metaphase 2?

Answer 54

Individual chromosomes assemble on the metaphase plate.

Question 55

What happens in meiosis 2 anaphase 2?

Answer 55

chromatids of individual chromosomes are pulled to opposite poles division of the contromeres

Question 56

What happens in meiosis 2 telophase 2?

Answer 56

``` Chromatids assemble chromosomes uncoil forming chromatin nuclear envelope becomes visible nuclear envelope reforms Cytokinesis results in 4 daughter cells genetically different . ```