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Cells Flashcards

1
Q

Resolution of light vs electron microscopes

A

200nm (light) vs 0.1nm (electron)

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2
Q

why do light microscopes have a lower resolution

A

the wavelength of light restricts the resolution

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3
Q

Details of electron microscope

A

beam of electrons focused by electromagnets in a vacuum environment

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4
Q

Why do electron microscopes need to be in a vacuum

A

so air particles don’t deflect the electron beam

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5
Q

TEM

A

Electrons passed through sample. Areas that absorb electrons appear darker.

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6
Q

SEM

A

Beam of electrons scatters across the surface and the pattern if scattering builds a 3D image

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7
Q

Disadvantage of electron microscope

A

vacuum means live samples can’t be observed
Complex staining system may introduce artefacts

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8
Q

Does SEM or TEM have lower resolution

A

SEM has lower resolution

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9
Q

What kind of solution is the homogenate placed in and why

A

cold (so enzymes are inactive), buffered (so no pH change), isotonic (so no bursting cells) solution

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10
Q

name for blended cells

A

homogenate

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11
Q

name for heaviest organelles at bottom

A

sediment or pellet

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12
Q

fluid at top after spinning centrifuge

A

supernatant

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13
Q

structure of nucleus

A

double membrane (envelope)
3000 nuclear pores
contains chromatin
nucleolus (site of ribosome production)
contains nucleoplasm

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14
Q

Rough ER structure and functions

A

flattened sacs enclosed in a membrane
ribosomes on surface
folds and processes proteins

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15
Q

SER structure and function

A

membrane bound sacs
produces and processes lipids

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16
Q

Golgi apparatus structure and function

A

fluid filled sacs
vesicles surrounding edges
processes and packages proteins and lipids
produces lysosomes

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17
Q

mitochondria structure and function

A

double membrane
christae (projections) and matrix
contains respiritory enzymes
site of aerobic respiration

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18
Q

centrioles structure and function

A

formed of microtubules
produce spindle fibres

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19
Q

ribosomes function

A

site of protein synthesis

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20
Q

lysosomes structure and function

A

vesicles bound by single membrane
contain digestive enzymes

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21
Q

Prokaryotic cell wall structure

A

rigid outer layer made of peptidoglycan

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22
Q

capsule structure and function

A

slimy layer which helps retain moisture and adhere to surfaces

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23
Q

pili

A

hair-like structures which help adhere to other cells

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24
Q

mesomes

A

folding of inner membrane which contain respiratory enzymes

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25
interphase
cell grows and organelles and genetic material duplicate
26
prophase
chromosomes condense and become visible centrioles split and move to opposite ends of cell nuclear envelope dissolves
27
metaphase
chromatids align at equator spindle fibres attach to them
28
anaphase
chromatids divide and move to edge of cell
29
telophase
chromosomes reach edge of cell nuclear envelope reforms cell prepares to split
30
cytokenesis
cytoplasm and cell membrane divides
31
equation to find out the number of cells after they divide for a given period of time
(og. number of cells x 2) ^(number of divisions)
32
Steps of binarry fission
circular DNA and plasmids duplicate and DNA attaches to cell membrane cell membrane grows between the two DNA molecules and divides the cytoplasm in two new cell wall forms New cell has one copy of DNA and a variable number of plasmids
33
why is it called the fluid mosaic model
The membrane is flexible and fluid and there are many different sized molecules within it
34
Proteins in CSM function
Extrinsic (on surface to act as receptors) Intrinsic (include carrier proteins to carry molecules across membrane) Also make the bilayer more stable
35
Cholesterol in CSM
makes membrane more rigid and prevents leakage as cholesterol is hydrophobic
36
glycolipids in CSM
Carbohydrate plus lipid Act as receptors Join to other cells to form tissues
37
glycoproteins in CSM
Carbohydrates plus proteins Act as receptors and neurotransmitters join to form tissues
38
Diffusion definition
Passive movement of small, non-polar, lipid-soluble molecules through the phospholipid bilayer. From high to low conc.
39
Facillitated diffusion
Requires a channel protein to transport polar/ charged molecules which are water soluble
40
osmosis
diffusion of water molecules from a high water potential to low water potential through a partially permeable membrane
41
active transport definition
movement of (any) molecule from low to high concentration . Requires ATP.
42
describe the process of active transport
molecule binds to carrier protein ATP is hydrolysed carrier protein changes shape molecule travels through ATP is synthesised carrier protein returns to original shape
43
exocytosis and endocytosis
transport large particles in vesicles vesicles fuse with csm and
44
co-transport
uses ions to move substances in and out of cells glucose moves into epithelial cell via active transport with sodium ions Sodium and potassium ions move out of cell into blood via active transport Glucose diffuses out of cell
45
factors affecting gas exchange
surface area steeper diffusion gradient diffusion distance temperature increases
46
features of viruses
much smaller than bacteria rely on a host to survive have genetic material, a capsid and an attachment protein viruses have no organelles such as cell membrane, plasmids etc.
47
non-specific immune response examples
inflammation lysozyme action (damages bacterial cell wall, in tears)
48
describe the process of phagocytosis
Phagocyte is attracted to the chemical products of the pathogen or recognises the receptors on its surface Binds to receptor and pathogen is activated Phagocyte engulfs pathogen and forms a phagosome (vesicle) around it Phagosome fuses with lysosome Lysozymes hydrolyse the pathogen Antigens are displayed on the phagocyte CSM
49
B cells description
formed in bone marrow and involved in humoral response antibody producing cells variable receptor shapes
50
T cells description
form in bone marrow then move to thymus gland where they mature involved in cell mediated response T helper cells- stimulate B cells and Tk cells to divide T killer cells- destroy infected pathogen cells by secreting cytosines
51
cell mediated response
T cells are activated as they bind to APC T cell divides by mitosis and produces clones Differentiates into Tk cells, Th cells and memory cells Some B cells are activated by Th cells
52
humoral response
B- cell triggered when encounters matching antigen engulfs antigen and digests it Prevents fractions of it on CSM Binds to complementary specific Th cell This activates B cell So it divides by mitosis into either plasma cells or B memory cells
53
what do plasma cells do
secrete antibodies complementary to the antigen originally encountered on the pathogen
54
structure of antibodies
4 polyeptide chains forming a Y shape two binding sites heavy chain (inside, long one) and light chain (outside, short)
55
function of antibodies
can clump many cells together (agglutination) so it's easier for phagocytes to find them
56
natural passive natural active artifical passive artifical active
exposure to antibodies via breast milk or placenta exposure to actual pathogen injection of antigen injection of actual pathogen via vaccination
57
why are vaccines not always successful
antigen on pathogen's surface can change
58
uses of monoclonal antibodies
direct therapy- target and destroy specific cells indirect therapy- cytotoxic drugs attached to the antibody diagnosis pregnancy testing
59
HIV stucture and function
lipid envelope with embedded attachment proteins protein capsid containing RNA and reverse transcriptase
60
HIV replication process
Binds to CD4 receptor Capsid fuses with CSM reverse transcriptase converts RNA to DNA HIV RNA moves into cell nucleus Host cell now has all the instructions to produce HIV components, so HIV can be replicated
61
ELISA test steps
the antigen of interest is immobilised specific antibody is added apparatus is washed secondary antibody is added, this is complementary to the first antibody add a substrate which is complementary to the secondary antigen colour change means enzyme is hydrolysed to antigen of interest is present
62
why are antibiotics ineffective on viruses
they kill bacteria by preventing it forming a cell wall. Viruses don't have a cell wall.
63
describe the role of the ribosome in polypeptide production
mRNA binds to ribosome aligna tRNA with complementary anticodons moves along the mRNA
64
what is a ribosomemade from
DNA, RNA, polypeptide
65
describe how bacteria divide
by binary fission daughter cells with a singular copy of circular DNA
66
why would enzyme denaturing be faster at a higher temperature
more kinetic energy means one enzyme denatures faster at a higher temperature
67
what is an advantage of secreting extracellular protease for bacteria
protease can hydrolyse proteins so can absorb amino acids
68
function of membrane- bound dipeptidases
hydrolyse dipeptides to release amino acids so they can cross the CSM
69
why would temperature need to be controlled in an experiment measuring rate of diffusion
diffusion will speed up in warmer temperatures
70
# 4 they defo have, 3 they may have structure of bacteria
no membrane-bound organelles 70s ribosomes no nucleus- single circular DNA molecule free in the cytoplasm and not associated with proteins a cell wall that contains murein, a glycoprotein. In addition, many prokaryotic cells have: one or more plasmids a capsule surrounding the cell one or more flagella.

Biology (8 decks)

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