save my exams cell diiciosn in eukaryotic and prokaryotic cells

Question 1

three phases of cell cycle

Answer 1

interphase
nuclear division
cell division

Question 2

three phases of interphase

Answer 2

G1 phase
S phase
G2 phase
cell increases in mass and size and carries out its normal cellular functions (eg. synthesising proteins and replicating its DNA ready for mitosis

Question 3

g1 phase

Answer 3

DNA in the nucleus replicates and cell grows

Question 4

s phase

Answer 4

interphase stage of the cell cyclerelatively shortCells make the RNA, enzymes and other proteins required for growth
synthesis of new dna

Question 5

g2

Answer 5

cell continues to grow and the new DNA that has been synthesised is checked and any errors are usually repaired
Other preparations for cell division are made (eg. the production of tubulin protein, which is used to make microtubules for the mitotic spindle)
error checking of newly synthesised dna

Question 6

nucleur divisiin

Answer 6

Follows interphase
Referred to as the M phase – M stands for mitosis
Cell growth stops during the M phase

Question 7

Cytokinesis

Answer 7

Once the nucleus has divided into two genetically identical nuclei, the whole cell divides and one nucleus moves into each cell to create two genetically identical daughter cells
In animal cells, cytokinesis involves constriction of the cytoplasm between the two nuclei and in plant cells a new cell wall is formed

Question 8

asexual reproductin

Answer 8

production of new individuals of a species by a single parent organism – the offspring are genetically identical to the parent

Question 9

asexual in unicellular

Answer 9

such as Amoeba, cell division results in the reproduction of a genetically identical offspring

Question 10

asexual in multicellular

Answer 10

new individuals grow from the parent organism (by cell division) and then detach (‘bud off’) from the parent in different ways. Some examples of these are budding in Hydra and yeast and runners from strawberries

Question 11

replacement of cells and repair of tissues

Answer 11

Damaged tissues can be repaired by mitosis followed by cell division
As cells are constantly dying they need to be continually replaced by genetically identical cells
In humans, for example, cell replacement occurs particularly rapidly in the skin and the lining of the gut
Some animals can regenerate body parts, for example, zebrafish can regenerate fins and axolotls regenerate legs and their tail amongst other parts

Question 12

growth of multiceeluar organisms

Answer 12

two daughter cells produced are genetically identical to one another (clones) and have the same number of chromosomes as the parent cell
This enables unicellular zygotes (as the zygote divides by mitosis) to grow into multicellular organisms
Growth may occur across the whole body of the organism or be confined to certain regions, such as in the meristems (growing points) of plants

Question 13

4 main stages of mitosis

Answer 13

Prophase
Metaphase
Anaphase
Telophase

Question 14

prophase

Answer 14

Chromosomes condense and are now visible when stained
The chromosomes consist of two identical chromatids called sister chromatids (each containing one DNA molecule) that are joined together at the centromere
The two centrosomes (replicated in the G2 phase just before prophase) move towards opposite poles (opposite ends of the nucleus)
Spindle fibres (protein microtubules) begin to emerge from the centrosomes (consists of two centrioles in animal cells)
The nuclear envelope (nuclear membrane) breaks down into small vesicles

Question 15

metaphase

Answer 15

Centrosomes reach opposite poles
Spindle fibres (protein microtubules) continue to extend from centrosomes
Chromosomes line up at the equator of the spindle (also known as the metaphase plate) so they are equidistant to the two centrosome poles
Spindle fibres (protein microtubules) reach the chromosomes and attach to the centromeres
Each sister chromatid is attached to a spindle fibre originating from opposite poles5

Question 16

anaphase

Answer 16

sister chromatids separate at the centromere
Spindle fibres begin to shorten
The separated sister chromatids (now called chromosomes) are pulled to opposite poles by the spindle fibres

Question 17

telophase

Answer 17

Chromosomes arrive at opposite poles and begin to decondense
Nuclear envelopes (nuclear membranes) begin to reform around each set of chromosomes
The spindle fibres break down

Question 18

cytokenesis

Answer 18

cytoplasm is divides forming two genetically identical cells and it takes place after the telophase stage of mitosis
two genetically identical daughter cells

Question 19

prophase thru images

Answer 19

Chromosomes are visible
The nuclear envelope is breaking down

Question 20

metaphase thru images

Answer 20

Chromosomes are lined up along the middle of the cell

Question 21

anaphase thru images

Answer 21

Chromosomes are moving away from the middle of the cell, towards opposite poles

Question 22

telophase thru images

Answer 22

Chromosomes have arrived at opposite poles of the cell
Chromosomes begin to decondense
The nuclear envelope is reforming

Question 23

cytokenisis thru images

Answer 23

Animal cells: a cleavage furrow forms and separates the daughter cells
Plant cells: a cell plate forms at the site of the metaphase plate and expands towards the cell wall of the parent cell, separating the daughter cells

Question 24

cancer treatments

Answer 24

Methotrexate - inhibits the synthesis of DNA nucleotides in cells
Vincristine and taxol - prevent the formation of the mitotic spindle

Question 25

carcinogen

Answer 25

agents that may cause cancer (eg. UV light, tar in tobacco smoke and X-rays). If the agent causes cancer it is described as carcinogenic

Question 26

benign

Answer 26

do not spread from their original site – these are known as benign tumours and do not cause cancer

Question 27

malignant

Answer 27

interfere with the normal functioning of the organ / tissue in which they have started to grow (eg. they may block the intestines, lungs or blood vessels
Malignant tumour cells can break off the tumour and travel through the blood and / or lymphatic system to form secondary growths in other parts of the body

Question 28

metastasis

Answer 28

The spreading of cancers in this way is known as metastasis
Metastasis is very dangerous as it can be very difficult to detect, locate and remove secondary cancers

Question 29

stages of cancer

Answer 29

1)oncogenes airse due to carcinogens
2)cancerous cells do not respond to signals from other cells so continues to divide
3)mitosis
4)cancerous cells not removed by immune systems
5)rapid mitosis
6)tumour gets bigger
7)tumour supplied w blood and lymph vessels if its malginant tumout then tumour cells spread in blood and lymph to other parts of the body
8)metastasis-tumour cells invade other tissues and secondary cancers form throughout the body

Question 30

process of binary fission

Answer 30

The single, circular DNA molecule undergoes DNA replication
Any plasmids present undergo DNA replication
The parent cell divides into two cells, with the cytoplasm roughly halved between the two daughter cells
The two daughter cells each contain a single copy of the circular DNA molecule and a variable number of plasmids

Question 31

purpose of binary fisssion

Answer 31

produce genetically identical daughter cells

Question 32

viraal replication

Answer 32

1)attachment -the virus attaches to the surface of the host cell
2)entry-the viral dna/rna enters the host cell
3)replication- viral dna and rna replicates and new viral protiens are made forming new capsid
4)assmegly -new viral particles are assembled
5)release-host cells lyses releasing the newly made virus