Cells and microscopy Flashcards Preview

AQA A-Level Biology Year 1 > Cells and microscopy > Flashcards

Flashcards in Cells and microscopy Deck (44)
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1

How does an optical microscope work?

direct light through specimen

light focused through objective lens

image viewed through eyepiece lens

2

What is calibration?

uses a stage micrometre (a second scale in micrometres on the slide)

3

How does cell fractionation work?

Cells broken open in homogeniser, tissue suspended in buffer solution and kept cold

filtered using a gauze - removes large tissue

centrifuge- pow speed , large organelles form pellet

supernatant spun again, smaller organelles form pellet

4

What is magnification?

how many times the bigger the image is

5

What is resolution?

the ability to see 2 structures very close together as separate structures

6

what are the advantages of optical microscopes

live specimens can be used

cheap

7

what are the disadvantages of optical microscopes?

lower resolving power

8

what are the advantages of electron transmission microscopes?

high resolving power

can see viruses, ribosomes, cell surface membranes

magnification up to x1,000,000

9

What are the disadvantages of electron transmission microscopes?

live specimens cannot be used

artefacts can occur

10

what are the advantages of an electron scanning microscope?

3D

High resolving power

11

what are the disadvantages of electron scanning microscope

no live specimens

artefacts can occur

12

How big are bacterial cells?

0.1- 10 micrometres

13

what are bacterial cell walls made from?

meurin

14

What do some bacterial cells secrete?

a capsule of mucilaginous slime

15

Give five comparisons of prokaryotic feels and eukaryotic cells

Prokaryotic- no true nucleus, eurkarytoic - nucleus with nuclear envelope

prokaryotic- no membrane bound organelles

prokaryotic- ribosomes are smaller - 70s, 80s in eukaryotic cells

Prokaryotic cell wall made is murein , in eukaryotes, cellulose

prokaryotic cell have plasmid DNA, DNA is linear in eukaryotes

16

What is the structure of the cell surface membrane?

Phospholipid bilayer

carrier proteins embedded in membrane

glycoproteins attaches to protein

17

what is the function of a cell surface membrane?

keeps unwanted substances out

allows transport of nutrients into cell and waste products out

18

What is the structure of the nucleus?

nuclear envelope with nuclear pores

nucleoplasm

contains DNA

19

What is the function of the nucleus ?

Nucleolus makes tRNA

Nucleus contains DNA

20

What is the structure of the mitochondrion ?

double membrane

inner layer forms cristae

mitochondrial matrix

has own dna and ribosomes

21

what is the function of the mitochondrion?

produces ATP during aerobic respiration

22

What is the structure of a lysosome ?

contains digestive enzymes (hydrolytic) which fuse with cell membrane to release

23

what is the function of the lysosome?

phagocytosis

recycling

24

what is the structure of a ribosome?

does not have a membrane

rRNA and protein

large unit - binding sites for tRNA

small unit- binding sites for mMRA

25

what is the role of a ribosome ?

site of translation

protein synthesis

26

what is the structure of the rough endoplasmic reticulum?

fluid filled cisternae

covered with ribosomes

vesicles can pop off

27

what is the function of the RER?

proteins folded into secondary and tertiary structures

28

what is the structure of the SER?

a series of tubes (cisternae )

29

what is the role of the SER?

synthesises lipids

30

what is the structure of the golgi apparatus?

stack of flattened sacs

plasma membrane

vesicles pinches off

cisternae

31

what is the function of the golgi?

packages and processes molecules for use in other parts of the cell or to export out the cell

32

What is the structure of the cell wall?

cellulose in plants

chitin in fungi

meurin in bacteria

permeable

cellulose microfibrils
embedded with pectin

33

what is the function of the cell wall?

provides cell with strength

resists beinf expanded

34

What is the structure of the vacuole?

tonoplast, thin membrane

cell sap

35

what is the function of the vacuole?

structural support

storage, waste , protection

36

what is the structure of chloroplasts

inner and outer membrane with empty space between

thylakoids , grana and stroma(dense fluid inside)

thylakoids contain chlorophyll

37

What is the function of chloroplasts?

site of photosynthesis

38

what is the structure of centrioles?

two rings of microtubules

positioned at right angles to each other

39

what is the functions of centrioles ?

produce spindle fibres

40

What is the cytoplasm?

70% water

metabolic reactions

41

what is a phospholipid ?

a lipid molecule with glycerol, two fatty acid chains and a phosphate group

42

PROKARYOTIC

What organelles are in a prokaryotic cell?

cell wall- muerin

cell surface membrane

circular DNA

food reserve granule

ribosomes

plasmids

slimy capsule

cytoplasm

flagellum

43

How much smaller are viruses than bacteria?

50x smaller

viruses are acellular

replicate inside a living cell

44

VIRUS

What is the viral structure?

Capsid made of capsomeres

genetic material