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Alevel Biology > Cells > Flashcards

Cells Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Cell membrane structure

A

phospholipid bilayer with embedded intrinsic and extrinsic proteins

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2
Q

cell membrane function

A

selectively permeable barrier
controls passage of substances in and out the cell
barrier between internal and external cell environment

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3
Q

Nucleus structure

A

nuclear pores, nucleolus, DNA and nuclear envelope

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4
Q

Nucleus function

A

site of transcription and pre-mRNA splicing - mRNA production
site of DNA replication
nucleolus make ribosomes
nuclear pore allows movement of substances to/from cytoplasm

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5
Q

mitochondria structure

A

double membrane with inner membrane folded into cristae
ribosomes in the matrix
small, circular DNA
enzymes in the matrix

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6
Q

mitochondria function

A

site of aerobic respiration
Produces ATP

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7
Q

Chloroplast structure

A

Thylakoid membranes stacked to form grana, linked by lamella
stroma contains enzymes
contains starch granules, small circular DNA and ribosomes

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8
Q

Chloroplast function

A

Chlorophyll absorbs light for photosynthesised to produce organic molecules

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9
Q

organisms containing chloroplasts

A

plants
algae

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10
Q

Golgi apparatus structure

A

fluid-filled, membrane-bound sacs

vesicles at edge

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11
Q

Golgi apparatus function

A

modifies proteins received from RER
packages them into vesicles to transport to cell membrane for exocytosis
makes lysosomes

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12
Q

Lysosome structure

A

type of golgi vesicle containing digestive enzyme

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13
Q

lysosomes function

A

contains digestive enzymes
e.g lysozymes to hydrolyse pathogen/cell waste products

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14
Q

Rough endoplasmic reticulum function

A

site of protein synthesis
fold polypeptides to secondary and tertiary structure
packaging into vesicles to transport to Golgi

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15
Q

smooth endoplasmic reticulum function

A

synthesises and processes lipids

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16
Q

cell wall function

A

provides structural strength, rigidity and support to cell
helps resist osmotic pressures

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17
Q

ribosome structure

A

small and large subunit
made of protein and rRNA
free floating in cytoplasm and bound to RER
70 in prokaryotes, mitochondria and chloroplasts

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18
Q

Ribosome function

A

site of translation in protein synthesis

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19
Q

rough endoplasmic reticulum structure

A

system of membranes with bound ribosomes
continuous with nucleus

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20
Q

smooth endoplasmic reticulum structure

A

system of membrane with no bound ribosomes

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21
Q

cell wall structure

A

in plant, fungal and bacterial cells
plants - made of microfibrils of cellulose
fungi - made of chitin
bacteria - murein

22
Q

cell vacuole structure

A

fluid-filled
surrounded by a single membrane called a tonoplast

23
Q

contrast prokaryotic and eukaryotic cells

A

prokaryotic cells are smaller
prokaryotes have no membrane bound organelles
prokaryotes have smaller ribosomes
prokaryotes have no nucleus-
circular DNA not associated with histones
prokaryotic cell wall made of
murein instead of cellulose/ chitin

24
Q

occasional features of prokaryotes

A

plasmids - loops of DNA
capsule surrounding cell wall - helps agglutination + adds protection
flagella for movement

25
Q

cell vacuole function

A

makes cells turgid - structural support
temporary store of sugars, amino acids
coloured pigments attract pollinators

26
Q

protein carriers

A

Bind with a molecule which causes a change in shape of the protein
this change in shape enables the molecule to be released to the other side of the membrane

26
Q

Protein channels

A

tubes filled with water enabling water-soluble ions to pass through the membrane
selective
channel proteins only open in the presences of certain ions when they bind to the protein

27
Q

features of viruses

A

non-living and acellular
contain genetic material, capsid and attachment proteins
some contain a lipid envelope and enzymes

28
Q

3 types of microscopes

A

optical
scanning electron microscopes
transmission electron microscopes

29
Q

magnification

A

image/actual
how many times larger the image is compared to the object

30
Q

resolution

A

the minimum distance between 2 objects which can still be viewed as separate
determined by the wavelength of light

31
Q

optical microscopes

A

beam of light used to create image
glass lens used for focusing
2D coloured image produced

32
Q

Evaluate optical microscopes

A

poorer resolution as long wavelength of light - small organelles not visible
lower magnification
can view living samples
simple staining method
vacuum not required

33
Q

TEM

A

beam of electrons passes through the sample used to create an image
focused using electromagnets
2D, black and white image produced
can see internal ultrastructure of cell
structures absorb electrons and appear dark

34
Q

evaluation TEMs

A

Highest resolving power
high magnification
extremely thin specimens
required
complex staining method
specimen must be dead
vacuum required

35
Q

SEM

A

Beam of electrons pass across
sample used to create image
focused using electromagnets
3D, black and white image
produced
electrons scattered across
specimen producing image

36
Q

Evaluation SEM

A

High resolving power
high magnification
thick specimens usable
complex staining method
specimen must be dead
vacuum required

37
Q

Why calibrate eyepiece graticule?

A

Calibration of the eyepiece is
required each time the objective
lens is changed
calibrate to work out the
distance between each division at that magnification

38
Q

Homogenisation

A

Process by which cells are broken open so organelles are free to be separated
done using homogeniser

38
Q

purpose of cell fractionation

A

break open cells and remove cell debris
so organelles can be studied

39
Q

homogenisation conditions

A

Cold reduces enzyme activity
preventing organelle digestion
Isotonic prevents movement of water by osmosis - no bursting / shrivelling of organelles
Buffered resists pH changes
preventing organelle + enzyme damage

40
Q

Ultra-centrifugation

A

Homogenate solution filtered to remove cell debris
solution placed in a centrifuge which spins at a low speed
initially
then increasingly faster speeds to separate organelles according to their density

41
Q

Differential centrifugation

A

supernatant first out is most dense = nuclei
spun at higher speeds
chloroplasts > mitochondria > lysosomes

42
Q

binary fission

A

involves circular DNA plasmids replicating
cytokinesis creates 2 daughter nuclei
each daughter cell has 1 copy of circular DNA and a variable number of plasmids

43
Q

cell cycle

A

interphase
nuclear division - mitosis or meiosis
cytokinesis

44
Q

interphase

A

Longest stage in the cell cycle
when DNA replicates (S-phase) and organelles duplicate while cell grows (G1&G2-phase)
DNA replicates and appears as two sister chromatids held by centromere

45
Q

mitosis

A

One round of cell division
two diploid, genetically
identical daughter cells
growth and repair (e.g. clonal
expansion)
comprised of prophase,
metaphase, anaphase and
telophase

46
Q

prophase

A

Chromosomes condense and
become visible
nuclear envelope disintegrates
in animals - centrioles separate & spindle fibre structure form

47
Q

metaphase

A

Chromosomes align along
equator of cell
spindle fibres released from
poles now attach to centromere and chromatid

48
Q

anaphase

A

Spindle fibre contracts (using
ATP) to pull chromatids,
centromere first, towards
opposite poles of cell
centromere divides in two

49
Q

telophase

A

Chromosomes at each pole
become longer and thinner
again
spindle fibres disintegrate +
nucleus reforms

50
Q

mitotic index

A

Used to determine proportion of cells undergoing mitosis
Calculated as a percentage OR decimal
num of cells in mitosis/ total num of cells
X100

Alevel Biology (14 decks)

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