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A-Level Biology > 2.1.1 Cell structure > Flashcards

2.1.1 Cell structure Flashcards

(61 cards)

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1
Q

resolution definition

A

ability to distinguish between two points on an image, smallest distance between 2 distinguishable points

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2
Q

magnification definition

A

size of an image compared to size of object

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3
Q

optical microscope pros

A

relatively cheap
easy to use
portable (use in field)
study whole living specimens

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4
Q

optical microscope magnification and resolution

A

x1500

200 nanometers

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5
Q

total magnification formula

A

total magnification = eyepiece lens magnifying power x objective lens magnifying power

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6
Q

photomicrograph definition

A

photograph of an image seen using an optical microscope

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7
Q

laser scanning microscopes

A

confocal microscopes
laser light scans object point by point and image produced by computer
depth selective
high resolution, high contrast
used in medical professions and biological research

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8
Q

how transmission electron microscope works

A 
chemically fixed (dehydrated and in vacuum) and stained (metal salts)
electrons pass through specimen and focused on screen / photographic plate
forms 2D black/white image
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9
Q

transmission electron micrograph magnification and resolution

A

x500,000

0.05 nanometers

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10
Q

scanning electron microscope magnification and resolution

A

x100,000

10 nanometers

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11
Q

how scanning electron microscope works

A

chemically fixed (dehydrated and in vacuum) and stained (metal salts)
electrons cause secondary electrons to bounce off specimen (focused on to screen)
produces 3D black/white image

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12
Q

electron microscope cons

A

large (not portable)
very expensive
need great deal of skill and training to use

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13
Q

how to observe unstained specimens

A

light interference
dark background behind illuminated specimen
adjusting iris diaphragm to control illumination of specimen
useful for observing living specimens

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14
Q

stain definition

A

coloured chemicals that bind to molecules / structures in / on specimen
makes specimen easier to see

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15
Q

methylene blue

A

all-purpose stain

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16
Q

differential staining definition

A

coloured chemicals binding to specific structures / molecules on specimen

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17
Q

acetic orcein

A

stains DNA and chromosomes dark red

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18
Q

eosin

A

cytoplasm

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19
Q

Sudan red

A

stains lipids

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20
Q

iodine in potassium iodide solution

A

cellulose in cell walls yellow

starch granules blue/black (purple under microscope)

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21
Q

how specimens prepared in laboratory

A

dehydrating specimen
embedding in wax (prevents distortion during slicing)
special instrument used to make thin cliches (sections)
sections stained and mounted in special chemical to preserve them

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22
Q

formula between image size, actual size and total magnification

A

image size = total magnification x actual size

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23
Q

longitudinal definition

A

lengthways

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24
Q

transverse definition

A

crossways

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25
oblique definition
slanting
26
eyepiece graticule definition
measuring device placed in eyepiece acts as ruler
27
stage micrometer definition
precise measuring device small scale placed on microscope stage used to calibrate value of eyepiece units at different magnifications 1mm
28
features of eukaryotic cells
``` nucleus (surrounded by nuclear envelope, containing DNA organised and wound into linear chromosomes) nucleolus within nucleus cytoplasm cytoskeleton plasma membrane membrane-bound organelles smell vesicles ribosomes ```
29
organelle definition
sub-cellular structure that performs one or more specific jobs
30
membrane-bound meaning
covered by membrane that keeps organelle separate from rest of cell
31
nucleus structure and function
``` surrounded by nuclear envelope chromatin around nucleolus nucleolus at centre (no membrane) control centre of cell stores genome transmits genetic information provides instruction for protein synthesis ```
32
nuclear envelope structure and function
double membrane separates contents of nuclear from rest of cell pores allow dissolved substances (e.g. steroid hormones) ribosomes and mRNA through
33
nucleolus function
where ribosomes made | contains RNA
34
chromatin structure and function
consists of DNA wound around histone proteins when not dividing, spread out or extended when about to divide, chromatin condenses and coils into chromosomes makes up nearly all organism’s genome
35
rough endoplasmic reticulum structure
system of membranes, continuous with nuclear membrane contains cisternae covered with ribosomes made up of phospholipid bilayer
36
rough endoplasmic reticulum function
compartmentalisation (maintains specific conditions needed in RER) separating proteins from cell cytoplasm holds ribosomes in place packaging proteins into transport vesicles
37
smooth endoplasmic reticulum structure
system of membranes, continuous with nuclear membrane contains fluid-filled cavities (cisternae) no ribosomes on its surface
38
smooth endoplasmic reticulum function
contains enzymes involved with lipid metabolism (synthesis of cholesterol, (phospho)lipids, steroid hormones) involved with synthesis and transport of lipids
39
Golgi apparatus structure
stack of membrane-bound flattened sacs | secretory vesicles bring materials to and from Golgi apparatus
40
Golgi apparatus function
``` modifies proteins (adds sugar/lipids to make glyco/lipoproteins, folds into 3D shape) protein packaged into vesicles (pinched off then stored in cell or moved to be part of plasma membrane or exported outside of cell) ```
41
mitochondria structure
``` spherical, rod-shaped or branched 2-5 micrometers long surrounded by two membranes (fluid-filled space in between) inner membrane folded into cristae inner part = fluid-filled matrix ```
42
mitochondria function
site of ATP production / aerobic respiration (doesn’t produce ATP!!) self-replicating abundant in cells with more metabolic activity
43
chloroplast structure
4-10 micrometers long only found in plant cells and some protoctists surrounded by double membrane inner membrane = continuous with stacks of flattened membrane sacs containing chlorophyll (thylakoids) thylakoid stack = granum fluid-filled matrix = stroma contains loops of DNA and starch granes
44
chloroplast function
site of photosynthesis first stage = light energy trapped by chlorophyll to make ATP (in granum) water split to supply hydrogen ions second stage = hydrogen reduces carbon dioxide (energy from ATP) to form carbohydrates (in stroma)
45
vacuole structure
surrounded by membrane (tonoplast) | contains fluid
46
vacuole function
only plant cells have large permanent vacuole filled with water and solutes maintains cell stability (pushes against cell wall, makes cell turgid) helps support plant if all cells turgid
47
lysosome structure
``` small bags formed from Golgi apparatus surrounded by single membrane contains hydrolytic (digestive) enzymes abundant in phagocytic cells (ingest and digest invading pathogens) ```
48
lysosome function
separates hydrolyitc enzymes from rest of cell can engulf and digest old cell organelles and foreign matter returns digested components to cell for reuse
49
cilia and undulipodia structure
protrusion from cell surrounded by cell surface membrane contain microtubules formed from centrioles
50
cilia and undulipodia function
movement of cell movement of mucus can contain receptors to detect signals from environment
51
organelles without membranes
ribosomes centrioles cytoskeleton cell wall
52
ribosome structure
small (20nm) spherical made of ribosomal RNA made in nucleolus (2 separate sub units then reassemble in cytoplasm) some free in cytoplasm, others attached to ribosome
53
ribosome function
protein synthesis free in cytoplasm = protein for inside cell bound to RER = mainly for proteins exported out of cell
54
centriole structure
two bundles of microtubules at right angle to each other microtubules (tubulin protein subunits) form cylinder to create bundle absent from cells of (higher) plants
55
centriole function
spindle forms from centrioles before cell division centrioles multiply and line up beneath cell surface membrane microtubules sprout outwards from each centriole to form cilium or undulipodium
56
cellulose cell wall structure
mesh of bundles of cellulose fibres
57
cellulose cell wall function
provide strength and support (of cell and whole plant) maintains shape of cell permeable (allows solutions through) prevents plant cells from bursting when turgid fungal cell walls made of chitin
58
cytoskeleton structure
network of protein structures in cytoplasm consists of: -rod-like microfilaments made up of subunits of actin. polymers of actin (7nm diameter) -intermediate filaments made up of variety of proteins (10nm diameter) -straight, cylindrical microtubules (18-30 nm diameter) -cystoskeletal motor proteins (myosins, kinesins, dyneins) molecular motors. enzymes that can bind to and allow hydrolysis of ATP as energy source)
59
cytoskeleton function
microfilaments give support and mechanical strength, keeps shape stable and allows cell movement microtubules provide shape and support, helps substances and organelles to move in cell (forms spindle fibres and track where motor proteins walk on) intermediate filaments anchor nucleus also extend between cells in some tissue for cell-cell signalling and adhering to basement membrane (stabilising tissues)
60
making and secreting protein method
gene (in chromatin) with instructions for protein is transcribed onto mRNA mRNA copied and exits nucleus via pores to ribosomes on RER instructions translated and protein assembled protein molecules pass into and through cisternae and hollow sacs of RER vesicles with protein within pinched off (by microtubules and motor proteins) and passed to Golgi apparatus vesicles fuse with Golgi apparatus for protein modification / packaging vesicles pinched off Golgi apparatus and go to plasma membrane vesicles fuse to plasma membrane and protein released to outside of cell (exocytosis, requires energy)
61
prokaryote structures
``` plasma membrane cytoplasm smaller ribosomes DNA and RNA (plasmid and nucleoid) less developed cytoskeleton cell wall (peptidoglycan) waxy capsule flagella pili ```

A-Level Biology (24 decks)

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