cell structure

Question 1

what are all cells surrounded by?

Answer 1

A cell surface membrane which controls which controls the exchange of materials between the internal cell environment and the external environment
- partially permeable
formed from a phospholipid bilayer (diameter of around 10nm)

Question 2

where are cell walls formed?

Answer 2

outside of the cell membrane and offer structural support to the cell
structural supporter is provided by the polysaccharide cellulose in plant
peptidoglycan in most bacterial cells

Question 3

what are narrow thread (surrounded by a cell membrane) which connect the cytoplasm of neighbouring plant cells?

Answer 3

plasmodesmata

Question 4

what does the nucleus cell contain?

Answer 4

chromatin
a complex of DNA and histone proteins
which is the genetic material of the cell

Question 5

what is the nucleus separated from the cytoplasm by ?

Answer 5

a double membrane ( the nuclear envelope) which has many pores

Question 6

why are nuclear pores important?

Answer 6

They are important channels for allowing mRNA and ribosomes to travel out of the nucleus, as well as allowing enzymes
(e.g. DNA polymerases) and signalling molecules to revel in

Question 7

what is chromatin?

Answer 7

the material from which chromosomes are made

chromosomes are made of sections of linear DNA tightly wound around proteins called histones

Question 8

what is the nucleolus?

Answer 8

the site of ribosome production

Question 9

what are mitochondria the site of?

Answer 9

the site of aerobic respiration

Question 10

what is mitochondria’s structure?

Answer 10

surrounded by double-membrane with the inner membrane folded to form cristae
the matrix formed by the cristae contains enzymes needed for aerobic respiration, producing ATP

Question 11

what is found in the matrix of the mitochondria?

Answer 11

small circular pieces of DNA (mitochondrial DNA)
ribosomes (needed for replication)

Question 12

what’s a structure that is larger than mitochondria and also surrounded by a double membrane?

Answer 12

chloroplast

Question 13

what structures are found in chloroplasts ?

Answer 13

membrane bound compartments called thylakoids contains chlorophyll stack to form structures called grana

Question 14

where is chlorophyll stored?

Answer 14

in thylakoids

Question 15

what are grana joined together by?

Answer 15

lamellae - thin and flat thylakoid membranes

Question 16

what are chloroplast the site of?

Answer 16

photosynthesis
- the light dependent stage takes place in thylakoids
- the light independent stage (calvin cycle) takes place in the stroma

Question 17

what are chloroplast the site of?

Answer 17

photosynthesis
- the light dependent stage takes place in thylakoids
- the light independent stage (calvin cycle) takes place in the stroma

Question 18

chloroplast components:

Answer 18

granum
lamella
thylakoid
ribosome
stroma
drop of lipids
chloroplast DNA
starch granule

Question 19

where are ribosomes found?

Answer 19

freely in the cytoplasm of all cells
or
as part of the rough endoplasmic reticulum

Question 20

where are ribosomes formed?

Answer 20

in the nucleolus
composed of equal amounts of ribosomal RNA (rRNA) and proteins

Question 21

where are 80S ribosomes found?

Answer 21

in eukaryotic cells
(composed of 60S and 40S subunits)

Question 22

where are 70S ribosomes found?

Answer 22

prokaryotes
mitochondria
chloroplasts

(composed of 50S and 30S subunits)

Question 23

what are ribosomes the site of?

Answer 23

site of translation
protein synthesis

Question 24

What is on the surface of the Rough Endoplasmic Reticulum ?

Answer 24

surface is covered in ribosomes

Question 25

what is the Rough Endoplasmic Reticulum formed from?

Answer 25

formed from continuous folds of membrane continuous with the nuclear envelope

Question 26

what does the rough endoplasmic reticulum do?

Answer 26

processes proteins made by the ribosomes

Question 27

what is the smooth endoplasmic reticulum involved in?

Answer 27

involved in production, processing and storage of lipids, carbohydrate and steroids

Question 28

what is the structure of the golgi apparatus?

Answer 28

flattened sacs of membrane

Question 29

what does the golgi apparatus do?

Answer 29

modified proteins and lipids before packaging them into golgi vesicles the vesicles then transport the proteins and lipids to their required destination proteins that go through the golgi apparatus are usually exported, put into lysosomes or delivered to membrane bound organelles

Question 30

what is the large permanent vacuole?

Answer 30

it is a sac in plant cells surrounded by the tonoplast, selectively permeable allows the cell to remain rigid

Question 31

what are vesicles?

Answer 31

membrane bound sac for transport and storage

Question 32

what are lysosomes?

Answer 32

specialist forms of vesicles which contain hydrolysis enzymes

Question 33

what are centrioles?

Answer 33

hollow fibres made of microtubules, two centrioles at right angles to each other form a centrosome , which organises the spindle fibres during cellular division

Question 34

what are microtubules?

Answer 34

make up cytoskeleton of the cell about 25nm in diameter made of alpha and beta tubulin combined to form dimers the diners are then joined by protofilaments the cytoskeleton is used to provide support and movement of the cell

Question 35

how many protofilaments in a cylinder make up a microtubule?

Answer 35

13

Question 36

what is cytoplasm made up of?

Answer 36

made up of organelles suspended in the gel like cytosol 70% of the cytoplasm is made up of water contains proteins, sugars, ions and fatty acids