Cell structure

Question 1

describe the structure ad function of the cell-surface membrane

Answer 1

1. phospholipid bilayer embedded with proteins
2. selectively permiable; controls passage of substances in and out of the cell
3. barrier between internal and external enviroments of cell

Question 2

describe the structure and function of the nucleus

Answer 2

1. controls cell activity throught he transcription of mRNA
2. nuclear pores allows substances (mRNA) to move between nucleus and cytoplasm
3. nucleolus makes ribosomes which are made of rRNA
4. Nuclear envelope, nuclear pores, nuleolus, DNA

Question 3

describe the structure and function of the mitochondria

Answer 3

1. Double membrane, inner membrane folded to form cristae; increase SA for reactions
2. Matrix- contains small 70s ribosomes, small circular DNA and enzymes involved in respiration
3. Site of aerobic respiration, producing/releasing ATP for energy

Question 4

describe the structure and function of the Golgi apparatus

Answer 4

1. 3 or more fluid filled membrane sacs with vesicles at the edge
2. receives proteins from the RER
3. modifies/processes proteins
4. packages modified proteins into vesicles, transport protein out of cell
5. also makes lysosomes

Question 5

describe the structure and function of the lysososme

Answer 5

1. vesicle containing lysozymes- hydrolytic enzymes

2. used to hydrolyse pathogens or worn out cells/cell components

Question 6

describe the structure and function of the ribosomes

Answer 6

1. free floating in the cytoplasm or bound to RER
2. NOT membrane bound ; made of 1 large sub-unit and 1 small sub-unit
3. site of protein synthesis; translation

Question 7

describe the structure and function of the rough endoplasmic reticulum

Answer 7

1. Ribosomes bound by a system of membranes
2. folds polypeptides into secondary and tertiary stuctures
3. packages folded polypeptides into vesiciles, transported to golgi

Question 8

describe the structure and fucntion of the smooth endoplasmic reticulum

Answer 8

1. system of membrane

2. synthesise and store lipids and carbohydrates

Question 9

describe the structure and function of the chloroplast

Answer 9

1. thylakoid membranes are stacked to form grana, grana are linked by lamellae
2. stroma is the fluid in the cell; contains the grana, starch granules and circular DNA
3. surrounded by a double membrane
4. chlorophyll absorbs light for photosynthesis to produce organic substances

Question 10

describe the structure and function of the cell wall

Answer 10

1. cellulose in plants
2. glycoprotein called murien; prokaryotes
3. chitin in fungi
4. rigid structure surrounding cell
5. prevents cell changing shape and bursting (lysis)

Question 11

describe the structure and function of the cell vacuole

Answer 11

1. contains cell sap; weak solution of sugars and salta
2. surrounding membrane is the tonoplast
3. maintains presure in the cell
4. isolates unwanted chemicals in the cell

Question 12

how are complex multicellular organsims organised?

Answer 12

1. speacialised cell- most basic structural/functional subunit of a living organism; speacialised for a particular fucntion
2. tissue- group of organised specialised cells joined and working together to perform a particular function
3. organs- group of organised tissue; joined together and working together to peform a particular function
4. organ system- group of organised organs; working together to peform a particular function

Question 13

comapre and contrast the structures of prokaryotes and eukaryotes

Answer 13

1. pro have no membrane bound organelles in the cytoplasm WHEREAS euk do
2. pro have no nucleus/ free floating DNA WHEREAS euk have a nucleus containing DNA
3. pro have circular DNA not associated with proteins WHEREAS euk have linear DNA associated with histone proteins
4. pro have a cell wall made of murein and peptidoglycan WHEREAS euk cell wall is made of cellulose
5. pro have smaller 70s ribosomes WHEREAS euk have larger 80s ribosomes
6. pros may have one or more plasmid, a capsule and/or flagella

Question 14

describe the structure of a virus

Answer 14

1. attatchment proteins; complementory to receptors on target cell
2. capsid made of lipids
3. DNA/RNA
4. acelluar- not made of or able to divide into cells
5. non-living- unable to reproduce without a host