Cell structure + all cells arise from other cells

Question 1

function of the nucleus

Answer 1

site of DNA replication
contains genetic code for each cell

Question 2

structure of the nucleus

Answer 2

-Nuclear envelope: double membrane

-nuclear pores : allows the passage of large molecules through

-nucleoplasm: granular jelly - like material making up the bulk of the nucleus.

-chromosomes : protein-bound linear DNA

-nucleolus : small spherical region within the nucleoplasm. manafactures ribosomal RNA and ribosome production

Question 3

structure of mitochondria

Answer 3

-double membrane
-inner membrane : cristae
-fluid centre called mitochondrial matrix
-loop of mitochondria DNA

Question 4

function of mitochondria

Answer 4

-Site of aerobic respiration
-site of ATP production
-its DNA codes for enzymes needed in respiration

Question 5

structure of the chloroplasts

Answer 5

found in plants and algae

-surrounded by double membrane

• contains thylakoids

-fluid filled stroma contains enzymes for photosynthesis

Question 6

functions of chloroplasts

Answer 6

-site of photosynthesis

Question 7

structure of ER

Answer 7

RER
- contains a folded membrane called cisternae which increase SA.
-have ribosome attached on cisternae

SER
-contains a folded membrane called cisternae which increase SA

Question 8

function of ER

Answer 8

RER:
-provides a large SA for the synthesis and transport of proteins

SER:
provides a large SA for the synthesis and transport of lipids and carbohydrates

Question 9

functions of Golgi apparatus:

Answer 9

1) modified, packages and transports proteins: adds carbohydrates to make glycoproteins

2) modifies, packages and transports lipids; produces secretory enzymes

Question 10

function of lysomes

Answer 10

• contains digestive enzymes : breaks down organelles for reuse of materials
• breaks down dead cells (autolysis)

-release enzymes to the outside of the cell to destroy material (exocytosis)

-hydrolysis phagocytic cells :

Question 11

structure of ribosomes:

Answer 11

-80S - found in eukaryotic cells, larger ribosome (25nm)

-70s - smaller ribosomes found in prokaryotic cells , mitochondria and chloroplast

Question 12

function of ribosomes

Answer 12

-site of protein synthesis

Question 13

structure of cell wall

Answer 13

found in plants and algae

plants- made up of microfibrils of the cellulose polymer

-fungi - made of chitin- a nitrogen containing polysaccharide

-bacteria: murein

Question 14

function of cell wall.

Answer 14

provide support + mechanical strength

Question 15

function of vacuoles

Answer 15

-maintains cell structure

-acts as a temporary energy store ; cell sap is a solution containing sugars and amino acids

-pigment may colour petals to attract pollinator

Question 16

Describe how prokaryotic cells are different from eukaryotic.

Answer 16

Smaller.
- Cytoplasm lacks membrane-bound organelles.
- Smaller ribosomes. (70s)
- No nucleus.
- A cell wall that contains murein.

Question 17

why are viruses classified as non living

Answer 17

-they are acellular ( not made up of cells)
- no cytoplasm
-no metabolism
-cannot self replicate

Question 18

describe the structure of viruses

Answer 18

• made up of nucleic acid: codes for protein
  -capsid protects genetic material
  -have attachment proteins: bind to the receptor .

Question 19

how do viruses replicate?

Answer 19

-attachment proteins bind to receptors on host cells.

-virus injects its viral nucleic acid into the host cell.

-virus uses the host cell’s machinery and resources, such as enzymes and ribosomes, to replicate viral particles.

New viral particles are released from the host cell.

Question 20

why is it so difficult to develop effective treatments against viruses?

Answer 20

-replicate inside living cells so difficult to kill them without killing the host cells.

Question 21

when does DNA replication takes place

Answer 21

interphase stage

Question 22

outline what happens during interphase

Answer 22

• G1) cell grows and protein synthesis

-S) DNA replicates –> chromosomes consists of two sister chromatids joined at centromere

G2) cell continues to grow + preperation for mitosis

Question 23

what is mitosis ?

Answer 23

• a parent cell divides to form two daughter cells.

Question 24

purpose of mitosis

Answer 24

-growth of multicelluar organisms

• cell replacement/ tissue repair
• asexual reproduction

Question 25

name the stages of mitosis

Answer 25

-prophase
-metaphase
-anaphase
-telophase

Question 26

outline what happens during phosphase

Answer 26

• Chromosomes condense - becomes visible

-2 centrioles seperate : move to opposite ends of the cell + mitotic spindle fibres form

-nuclear envelope starts to break down

Question 27

outline what happens during metaphase

Answer 27

–chromosomes line up at the cell equator

-become attached to the mitotic spindle fibre by their centromeres

Question 28

outline what happens during anaphase

Answer 28

• centromeres divided - seperates each pair of sister chromatids

-spindle fibre contract- pulls chromatids to opposite poles of the spindle

-chromatids: v shaped

Question 29

outline what happens during telophase

Answer 29

-chromatids reach the opposite poles on the spindle

• uncoil and become long again: called chromosomes

-nuclear envelope forms around each group of chromosomes : 2 nuclei form

Question 30

outline what happens during cytokinesis

Answer 30

• cytoplasm divide into two
  -forms 2 daughter cells

Question 31

mitoic index formula

Answer 31

number of cells in mitosis / total number of cells

x100

Question 32

define tumour

Answer 32

-mass of abnormal cells
undergo uncontrollable cell division

Question 33

cancer treatments

Answer 33

-chemotherapy : disrupts the cell cycle by stopping the DNA synthesis (s)

Question 34

process of binary fission

Answer 34

1) circular DNA and plasmids replicates

2) division of cytoplasm: Produces two daughter cells , each with a single copy of the circular DNA and a variable number of plasmids

Question 35

HIV replication

Answer 35

1) HIV is transported in the blood
2) HIV uses its attachment proteins which bind to the receptors in the host cells
3)the nucleic acid enter the host cell
4) nucleic acid replicates inside the host cell
5) reverse transcriptase makes DNA from RNA
6) viral DNA is inserted into the host cells DNA inside the host cells nucleus
7) DNA is transcribed into the mRNA in the nucleus
8) mRNA is translated into new viral particles
9) virus is assembled and released from the cell