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

Cells and microscopy Flashcards

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1
Q

How does an optical microscope work?

A

direct light through specimen

light focused through objective lens

image viewed through eyepiece lens

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2
Q

What is calibration?

A

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

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3
Q

How does cell fractionation work?

A

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

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4
Q

What is magnification?

A

how many times the bigger the image is

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5
Q

What is resolution?

A

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

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6
Q

what are the advantages of optical microscopes

A

live specimens can be used

cheap

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7
Q

what are the disadvantages of optical microscopes?

A

lower resolving power

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8
Q

what are the advantages of electron transmission microscopes?

A

high resolving power

can see viruses, ribosomes, cell surface membranes

magnification up to x1,000,000

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9
Q

What are the disadvantages of electron transmission microscopes?

A

live specimens cannot be used

artefacts can occur

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10
Q

what are the advantages of an electron scanning microscope?

A

3D

High resolving power

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11
Q

what are the disadvantages of electron scanning microscope

A

no live specimens

artefacts can occur

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12
Q

How big are bacterial cells?

A

0.1- 10 micrometres

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13
Q

what are bacterial cell walls made from?

A

meurin

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14
Q

What do some bacterial cells secrete?

A

a capsule of mucilaginous slime

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15
Q

Give five comparisons of prokaryotic feels and eukaryotic cells

A

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

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16
Q

What is the structure of the cell surface membrane?

A

Phospholipid bilayer

carrier proteins embedded in membrane

glycoproteins attaches to protein

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17
Q

what is the function of a cell surface membrane?

A

keeps unwanted substances out

allows transport of nutrients into cell and waste products out

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18
Q

What is the structure of the nucleus?

A

nuclear envelope with nuclear pores

nucleoplasm

contains DNA

19
Q

What is the function of the nucleus ?

A

Nucleolus makes tRNA

Nucleus contains DNA

20
Q

What is the structure of the mitochondrion ?

A

double membrane

inner layer forms cristae

mitochondrial matrix

has own dna and ribosomes

21
Q

what is the function of the mitochondrion?

A

produces ATP during aerobic respiration

22
Q

What is the structure of a lysosome ?

A

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

23
Q

what is the function of the lysosome?

A

phagocytosis

recycling

24
Q

what is the structure of a ribosome?

A

does not have a membrane

rRNA and protein

large unit - binding sites for tRNA

small unit- binding sites for mMRA

25
Q

what is the role of a ribosome ?

A

site of translation

protein synthesis

26
Q

what is the structure of the rough endoplasmic reticulum?

A

fluid filled cisternae

covered with ribosomes

vesicles can pop off

27
Q

what is the function of the RER?

A

proteins folded into secondary and tertiary structures

28
Q

what is the structure of the SER?

A

a series of tubes (cisternae )

29
Q

what is the role of the SER?

A

synthesises lipids

30
Q

what is the structure of the golgi apparatus?

A

stack of flattened sacs

plasma membrane

vesicles pinches off

cisternae

31
Q

what is the function of the golgi?

A

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

32
Q

What is the structure of the cell wall?

A

cellulose in plants

chitin in fungi

meurin in bacteria

permeable

cellulose microfibrils
embedded with pectin

33
Q

what is the function of the cell wall?

A

provides cell with strength

resists beinf expanded

34
Q

What is the structure of the vacuole?

A

tonoplast, thin membrane

cell sap

35
Q

what is the function of the vacuole?

A

structural support

storage, waste , protection

36
Q

what is the structure of chloroplasts

A

inner and outer membrane with empty space between

thylakoids , grana and stroma(dense fluid inside)

thylakoids contain chlorophyll

37
Q

What is the function of chloroplasts?

A

site of photosynthesis

38
Q

what is the structure of centrioles?

A

two rings of microtubules

positioned at right angles to each other

39
Q

what is the functions of centrioles ?

A

produce spindle fibres

40
Q

What is the cytoplasm?

A

70% water

metabolic reactions

41
Q

what is a phospholipid ?

A

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

42
Q

PROKARYOTIC

What organelles are in a prokaryotic cell?

A

cell wall- muerin

cell surface membrane

circular DNA

food reserve granule

ribosomes

plasmids

slimy capsule

cytoplasm

flagellum

43
Q

How much smaller are viruses than bacteria?

A

50x smaller

viruses are acellular

replicate inside a living cell

44
Q

VIRUS

What is the viral structure?

A

Capsid made of capsomeres

genetic material

AQA A-Level Biology Year 1 (6 decks)

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