Topic 3 - cell division

Question 1

Nucleus function

Answer 1

Contains chromosomes made of DNA + contain genes that control the synthesis of proteins

Question 2

Mitochondria function

Answer 2

Site of aerobic respiration to produce energy

Question 3

Lysosome defi.

Answer 3

• Breakdown of unwanted structures
• destruction of whole cells to be replaced

Question 4

RER defi.

Answer 4

• rough endoplasmic reticulum
• ribosomes attached to surface
• proteins made on ribosomes are transported through here to other parts of cell

Question 5

SER defi.

Answer 5

• smooth endoplasmic reticulum
• makes lipids + steroids

Question 6

Golgi apparatus defi.

Answer 6

Modifies proteins and packages them into vesicles for transport

Question 7

Centriole defi.

Answer 7

• Formation of spindle during nuclear division

Question 8

What is the conversion of mm to um ?

Answer 8

X by 1000

Question 9

Mesosome defi.

Answer 9

• infold in wall of prokaryotes
• replication of DNA

Question 10

Pili defi.

Answer 10

• hair like structures on the end of prokaryotes that allow them to stick to surfaces

Question 11

Slime capsule defi.

Answer 11

• protects prokaryotic cells from physical and chemical attacks

Question 12

Plasmid defi.

Answer 12

Circular molecule of DNA

Question 13

What is the cell wall made from in prokaryotic cells ?

Answer 13

Peptidoglycan

Question 14

What structures occur in prokaryotic cells but not Eukaryotic ?

Answer 14

Plasmid , pili, slime capsule, flagellum, mesosome

Question 15

What is the name of a cell containing half the number of chromosomes of a normal body cell and give an example.

Answer 15

Haploid , sperm + egg cells

Question 16

What is the name of the layer that surrounds an egg cell ?

Answer 16

Zona pullcida

Question 17

What are the stages of fertilisation ?

Answer 17

• Sperm reaches ovum
• chemicals released from cells surrounding ovum triggering acrosome reaction
• acrosome swells, fusing with sperm cell surface
• digestive enzymes released
• digest through follicle cells and zona pullcida
• sperm fuses with ovum membrane
• nucleus enters ovum
• enzymes from lysosomes in ovum thicken zona pullcida (cortical reaction)
• nuclei of ovum + sperm fuse

Question 18

Name the features of a sperm cell that make it efficient at its function

Answer 18

• Acrosome which contains digestive enzymes to break through egg wall
• many mitochondria from energy for swimming
• flagellum to swim
• haploid nucleus

Question 19

Describe how cells become specialised

Answer 19

• signals cause different genes to become switched on and off
• only genes that are switched on will be transcribed
• different proteins that are transcribed the the cells different structure and functions

Question 20

Totipotent definition

Answer 20

A cell that is able to differentiate into all cell types

Question 21

Pluripotent definition

Answer 21

Can differentiate into most cells except placenta and umbilical cord

Question 22

Describe how methylation affects DNA

Answer 22

Methylation is the addition of methyl groups to DNA preventing transcription factors from binding and the gene being transcribed
The gene is therefore “switched off”
Can be cause by environmental , lifestyle or age.

Question 23

Describe how acetylation affects DNA and genes

Answer 23

Acetylation is the addition of an acetyl group to the host one tails
It prevents DNA winding as tightly around the histone exposing the DNA and genes “switch on”
This allowed the gene to be transcribed

Question 24

Name the 3 parts of the cell cycle

Answer 24

interphase, mitosis, cytokinesis

Question 25

what is the cell doing during interphase?

Answer 25

cell mass is increasing and normal cell functions are carried out

Question 26

what are the 4 phases that occur in interphase?

Answer 26

G1, S, G2, G0

Question 27

What happens in th s phase of interphase?

Answer 27

DNA in nucleus replicates

Question 28

What happens in the G1 phase?

Answer 28

Protein synthesis

Question 29

What hsppens in the G2 Phase?

Answer 29

Organelle replication, protein synthesis

Question 30

How does a cell enter the G0 phase?

Answer 30

If a checkpoint ( one at g1 and one at g2) detects a fault in the replication of organelles and dna then the cell will be sent here to repair errors

Question 31

What is the function of Cytokinesis? (How does it happen?

Answer 31

(animal)cell pinches at equatorial plate by filaments and cell contracts until split in two (plant) a cell plate is synthesised between two nuclei

Question 32

explain what happens during Prophase

Answer 32

* DNA condenses into chromosomes consisting of two identicle sister chromatids joined at a centromere *centrosomes move to opposite poles of the nucleus * nuclear envelope breaks down

Question 33

explain what happens during metaphase

Answer 33

* chromosomes line up along equatorial plate * spindle fibres attatch to the centromere of the sister chromatids pulling them apart

Question 34

describe what happens during Anaphase

Answer 34

Sister chromatids pulled apart at the centromere by shortening spindle fibres towards the centrosomes at opposite poles.

Question 35

explain what happens during Telophase

Answer 35

* chromosomes begin to condense at opposite poles * the nuclear envelope begins to reform around the chromosomes * spindle fibres break down

Question 36

why is mitosis important?

Answer 36

* growth of multicellular organisms(zygote needs it to form a baby) * replacement and repair of damaged tissues * Asexual reproduction