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AQA A Level biology > cells > Flashcards

cells Flashcards

(53 cards)

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1
Q

eukaryotic cell is…

A

cell with membrane bound organelles
can become specialised by process of differentiation

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2
Q

cell surface membrane

A

phospholipid bilayer
controls entry and exit of substances, sometimes requires active transport or membrane proteins

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3
Q

nucleus

A

double membrane
contains chromosomes

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4
Q

mitochondria

A

double membrane
fold called cristae (large SA)
site of aerobic respiration

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5
Q

chloroplasts

A

plants only
double membrane
site of photosynthesis
geranium (stack) individually called thylakoids
geranium connected by lamella
stroma (fluid)

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6
Q

Golgi apparatus/body

A

modifies proteins
role in ‘packaging’ and secretion of proteins
made of flattened sacs called cisternae
circles pf diagrams are Golgi vesicles which take proteins and get them ready for export

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7
Q

lysosomes

A

small membranous vesicles
breaks down ‘unwanted’ cells/organelles
contain lysozymes (enzymes that kill pathogens)

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8
Q

ribosomes

A

round shaped organelles that synthesise protein
some attach to surface of rough ER

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9
Q

rough endoplasmic reticulum

A

large no. of ribosomes attached to surface
synthesise and ‘make changes’ to proteins

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10
Q

smooth endoplasmic reticulum

A

no. of ribosomes on surface
lipid synthesis
toxin modification
glycogenesis

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11
Q

cell wall

A

plants only
determines strength, shape and support
composed of cellulose
controls tutor pressure

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12
Q

vacuole

A

membranous sacs
store water, nutrients and waste products

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13
Q

prokaryotic cells

A

no membrane bound organelles
smaller than eukaryotes
smaller ribosomes
DNA is not encoded in nucleus
DNA= singular circular molecule, not associated with proteins
may have plasmids, capsule and flagella

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14
Q

basic structure of a virus is…

A

genetic material can be DNA or RNA
capsid coats material, protects it
attachment proteins- attach to receptors on host cells and allow the virus to enter and inject genetic material

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15
Q

magnification is…

A

how large an image is compared to real life

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16
Q

resolution is…

A

the minimum distance where two objects are distinguishable as two objects

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17
Q

features of an optical microscope

A

light focused through condenser lens, then through specimen where certain wavelengths are filtered
light passes through objective sense, then to eye piece sense to provide visible images
max mag= x1500
max res= 200um
can view live specimens and observe processes

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18
Q

features of transmission electron microscope

A

electrons pass through specimen, denser parts absorb more electrons so appear darker ]max mag= x500000 max res= 0.1nm
cannot view live specimens or processes as interior is a vacuum so specimen has to be sliced very thinly
requires extensive staining process that can lead to artefacts

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19
Q

features of scanning electron microscope

A

produces 3D image
electrons ‘bounce off’ specimen and are detected at multiple detectors
max mag= x100000
mag res= 20nm

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20
Q

how is actual size measured

A

using eye piece graticule, calibrated using a micrometer
1. line up graticule with micrometer
2. count no. of graticule division that correspond with a set measurement on stage micrometer
3. calc. distance in um of one division on eye piece graticule

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21
Q

ultracentrifugation is…

A

used to separate cell components or to get s cell-free liquid

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22
Q

how to ultracentrifuge

Study These Flashcards
A
  1. cells homogenised to break open cells
  2. places in cold (prevents enzyme activity), isotonic (prevents osmosis) and buffered solution (prevents pH changes that could denature proteins)
  3. filter to get rid of debris
  4. centrifuge at low speed, separates nuclei as pellets at bottom of tube, solution called supernatant
  5. centrifuge at high speed, separates mitochondria and chloroplasts as pellets and the bottom
  6. repeat again and again, ER and Golgi next
  7. ends up as cell free solution
23
Q

cell cycle includes…

Study These Flashcards
A

G1, S phase, and G2

24
Q

mitosis is…

Study These Flashcards
A

nuclear division, eukaryotic cell divides to produce 2 genetically identical daughter cells
division of the nucleus is mitosis, and division of the cell is cytokinesis

25
stage 1 of mitosis is...
interphase= G1- proteins synthesis and cell grows large S phase- DNA replication G2- additional growth
26
stage 2 of mitosis is...
prophase= chromosomes condense and become visible nuclear envelope breaks down mitotic spindle forms
27
stage 3 of mitosis is...
metaphase= chromosomes line up at the equator mitotic spindles attach to the centromeres
28
stage 4 of mitosis is...
anaphase= sister chromatids separate at the centromere and are pulled to opposite poles of the celery the mitotic spindle
29
stage 5 of mitosis is...
telophase= spindle fibres disappear and nuclear envelope reformed chromosomes start to de-condense cytokinesis occurs
30
what happens if mitosis goes wrong?
mutations cause uncontrolled cell division, forming tumours and caner many cancer treatments directed at controlling rate of cell division
31
most prokaryotes don't undergo mitosis, they...
undergo binary fission circular DNA and plasmids are replicated cytoplasm divides, so a single copy of circular DNA and variable plasmid copy numbers
32
structure of a cell surface membrane
phospholipid bilayer glycoproteins and glycolipids (aid in cell attachment) channel proteins and carrier proteins (allow large/polar/water soluble molecules past the membrane cholesterol (restricts movement to provide stability)
33
simple diffusion is...
movement of small, non polar particles through the phospholipid bilayer
34
facilitated diffusion is...
movement of larger molecules through channel proteins or carrier proteins channel proteins= molecules pass through carrier proteins= molecules move in, tertiary structure of protein changes, allows molecule to enter the cell
35
active transport is...
movement against concentration gradient using carrier proteins, requiring ATP hydrolysis
36
co-transport is...
2 molecules transported together, one going down conc. gradient, other going up e.g. small intestine= Na+ and glucose transported from lumen to epithelium Na+ actively transported into blood, K+ goes into epithelium from blood, glucose goes into blood via facilitated diffsuion
37
osmosis is...
movement of water molecules across selectively permeable membrane from high water potential to low water potential (relative tendency of water to move from one place to another)
38
adaptations of cell membranes are...
increases SA (folds) increased no. of channel/carrier proteins
39
what does each type of cell have on their surface
specific molecules to identify things like pathogens, abnormal body cells, toxins
40
antigens are...
foreign proteins on cell-surface membrane that stimulate an immune response
41
phagocytosis and its steps are...
engulfment of pathogen by a phagocyte 1. phagocyte attracted to pathogen and binds to receptors 2. pathogen engulfed by phagocyte via endocytosis, phagosome formed (visible containing pathogen) 3. lysosomes fuse with pathogen, lysozymes break down pathogen into soluble materials lymphocytes= B (mature in bine marrow, involved in humeral response) + T cells (mature in thymus gland, involves in cell-mediated response)
42
the cell-mediated response is...
T cell receptors binds to antigen presenting cell, stimulates differentiation of T cells, Helper T cells formed, cytoxic T cells (produce perforin which makes holes in cell membrane) can also stimulate phagocytosis
43
the humoral response is...
Helper T cells stimulate B cells to rapidly divide by mitosis to form clones of plasma checks (clonal selection) plasma cells produce antibodies that have specific shape to antigen so they attach and destroy the pathogen agglutination= antigen-antibody complex all stick together, allows for easier digestion via phagocytosis
44
antibodies are...
proteins with complementary binding sites to antigens, and destroy the pathogens involved in humoral response
45
features of vaccination...
dead/inactive pathogen initiates a primary response leading to formation of memory B cells upon reinfection, secondary response is stimulated provides herd immunity
46
ethical issues of vaccination are...
should they be compulsory? who should they test on? are they 100% effective long-term?
47
active and passive immunity is...
active= results from production by immune system in response ti presence of antibody passive= results from introduction of antibodies from another person/animal
48
monoclonal antibodies are...
type of antibody isolated from a single clone of B cells used in drug testing (specific ti the target if the drug) ethical issues= use mice to produce them
49
ELISA is and its steps are...
test used in detection of antigens 1. antigen of interest immobilised 2. monoclonal antibodies added + bind to appropriate antigen 3. apparatus washed to remove unbound antigens 4. more monoclonal antibodies added, linked to colour changing enzymes and bind to antigens 5. washed again 6. complementary substrate to enzyme added, triggering colour change upon binding, thus showing presence of antigen
50
features of HIV...
spikes on the edge called glycoproteins capsid to protect the genetic material
51
HIV replication
attaches to CD4 receptors on the Helper T cells RNA + enzymes enter host T cell viral RNA copied to cDNA by reverse transcriptase cDNA moves into T cell nucleus where it is transferred and translated using host machinery to produce viral proteins that makes new viruses new virus particles break off T cell membranes
52
how does HIV cause AIDs?
helper T cell dies when new HIV particles break off membrane decreased B cell stimulation= decreased immunity vulnerable to infection that are fatal HIV drugs often target reverse transcriptase
53
antibiotics are...
ineffective against viruses kill bacteria

AQA A Level biology (8 decks)

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