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Biology A Level > Cells > Flashcards

Flashcards in Cells Deck (29):
1

Nucleus, nuclear envelope, nucleolus
structure

nucleus surrounded by double membrane (nuclear envelope), contain pores
nucleolus contains RNA, no membrane
chromatin is genetic material, DNA wound round histone proteins
cell not dividing: chromatin spread out/extended
about to divide:chromatin condenses, coils tightly into chromosomes - make up organism's genome

2

nuclear envelope function

separates contents of nucleus from rest of cell
some regions: outer, inner nuclear membranes fuse together - dissolved substances (ribosomes) pass
pores enable larger substances (mRNA) out, steroid hormones from cytoplasm in.

3

nucleolus function

where ribosomes are made
chromosomes contain genome

4

nucleus function

control centre
stores organism's genome
transmits genetic info
provides instructions for protein synthesis

5

RER structure

system of membranes
contain fluid-filled cavities (cisternae)
coated with ribosomes

6

RER function

intracellular transport system: cisternae form channels for transporting substances around cell
large SA for ribosomes - assemble amino acids into proteins, pass through membrane into cisternae, transported to Golgi apparatus

7

SER structure

contains fluid-filled cavities (cisternae)
no ribosomes

8

SER function

contains enzymes - catalyse reactions involved with lipid metabolism
absorption, synthesis, transport of lipids

9

Golgi apparatus structure

stack of membrane-bound flattened sacs
have secretory vesicles - transport materials to and from GA

10

Golgi apparatus function

modifies proteins
proteins packaged into vesicles, pinched off, stored in cell/incorporated in plasma membrane/exported out cell

11

Mitochondria structure

2-5 μm long
outer and inner membrane (fluid between)
inner folded into cristae
inner=fluid filled matrix

12

Mitochondria function

site of ATP production = aerobic respiration
self-replicating
lots metabolic activity = lots mitochondria

13

chloroplasts structure

4-10 μm long
in palisade mesophyll layer
double membrane
inner membrane = stacks of flattened membrane sacs (thylakoids) - contain chlorophyll
stack of thylakoids = granum
fluid-filled matric = stroma
contain loops of DNA and starch grains

14

chloroplasts function

1st stage of photosynthesis, in grana: light energy trapped by chlorophyll make ATP
water split - supply hydrogen ions
2nd, in stroma:energy from ATP - hydrogen reduces carbon dioxide to make carbohydrates

15

Vacuole structure

contains fluid
surrounded by tonoplast (membrane)

16

Vacuole function

maintains cell stability
pushes cell wall = supports, cell turgid
filled with water and solutes

17

Lysosomes structure

formed from GA
small bags surrounded by membrane
contain hydrolytic enzymes (digestive)

18

Lysosomes function

keep powerful enzymes from rest of cell
ingest, digest pathogens
engulf old organelles and foreign matter
return digested components to cell for reuse

19

Cilia and Undulipodia structure

protrusions from cell
surrounded by cell surface membrane
contains microtubules
formed from centrioles

20

Cilia and Undulipodia function

in epithelial cells lining airways to move mucus
acts as antenna - contains receptors - cell detects signals about env.

21

Ribosomes structure

20nm diameter
made of ribosomal RNA (rRNA)
remain in cytoplasm or attach to ER

22

Ribosomes function

in RER: synthesising proteins - exported out cell
free in cytoplasm: assemble proteins - used in cell

23

Centrioles structure

2 bundles of microtubules at right angles
microtubules made from tubulin protein subunits into cylinder

24

Centrioles function

before cell division - threads of tubulin (spindle) forms from centrioles
chromosomes attach to middle of spindle
motor proteins walk along tubulin threads = pull chromosomes opposite ends of cell
formation of cilia, undulipodia (from microtubules)

25

Cytoskeleton structure

network of protein structures within cytoplasm
rod-like microfilaments, intermediate filaments, striahgt cylindrical microtubules
cytoskeletal motor proteins; myosins, kinesins, dyneins =molecular motors, and enzymes, allows hydrolysis of ATP as energy source

26

Cytoskeleton function

support, strength to cell's shape, cell movement
help organelles move through cytoplasm
form track along which motor proteins walk
form spindle before cell divides (chromosomes moved)
intermediate filaments = anchor nucleus, extend between cells - signalling

27

Cellulose cell wall structure

made of bundles of cellulose fibres

28

Cellulose cell wall function

prevent cells from bursting when turgid
strength, support, maintain shape
permeable, allows solutions to pass

29

Prokaryotic cells

Plasma membrane
Cytoplasm
Ribosomes
DNA
RNA

smaller, less developed cytoskeleton, no centrioles,