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BIO PAPER 1 > Cell structure > Flashcards

Cell structure Flashcards

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1
Q

What is a eukaryotic cell (key definition)

A

a cell with MEMBRANE BOUND ORGANELLES

in plant and animal cells

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2
Q

structure and function of cell membrane

A

It is a phospholipid bilayer and its function is to allow extracellular substances to enter and for waste to exit the cell

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3
Q

structure and function of nucleus

A

is has a double membrane ( more efficient control of transport in and out )

contains chromosomes which consist of protein bound DNA (histones)

One or more NUCLEOLI which is for rRNA synthesis

Nuclear pores are there to transport transcribed mRNA into the cytoplasm

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4
Q

Structure and function of mitochondria

A

Has a double membrane

has cristae folds for a large surface area

site of aerobic respiration(ATP)

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5
Q

Structure and function of chloroplasts

A

Site of photosynthesis in plants

Stroma, thylakoids(granum) , lamella ( connects granum)

double membraned

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6
Q

Structure and function of the golgi body

A

Modification of proteins

Packaging and secretion of proteins (in Golgi vesicles)

made of cisternae

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7
Q

Structure and function of lysosmes

A

Small membranous vesicles

get rid of unwanted cells or organelles

contain lysozymes which destroy pathogens

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8
Q

Structure and function of ribosomes

A

Organelles that synthesise protein

some are attached to rough endoplasmic reticulum

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9
Q

structure and function of rough endoplasmic reticulum

A

has a large number of ribosomes attached to surface

synthesise and modify proteins

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10
Q

smooth endoplasmic reticulum

A

doesn’t have ribosomes attached

for lipid synthesis, toxin modification and glycogenesis

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11
Q

Cell wall structure and function

A

for strength and shape of cell

made of cellulose

controls turgidity ( regulates water content)

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12
Q

Vacuole structure and function

A

membranous sacs

stores water nutrients and waste products

much larger in plant cells

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13
Q

what type of cells can become specialised

A

eukaryotic cells

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14
Q

what is a prokaryotic cell and how are they different to eukaryotic

A

a cell with no membrane bound organelles

smaller than eukaryotes

they have smaller ribosomes

they have plasmids (rings of DNA for extra genetic material)

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15
Q

Where is prokaryotic DNA found

A

It is free in the cytoplasm as there is no nucleus

it is a singular circular molecule

also found in plasmids

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16
Q

what surrounds a prokaryotic cell and why

A

a capsule that is for attachment and protection from phagocytosis

17
Q

why can prokaryotes move

A

as they have one or more flagella on the exterior of the cell

18
Q

Full structure of viruses

A

Has genetic material (either DNA or RNA) encased in a CAPSID to protect it

have attachment proteins to attach to receptors of host cells to allow the virus to inject genetic material in for it to be replicated and produce more viruses

19
Q

What is magnification

A

How large the image is compared to real life

20
Q

What is resolution

A

the minimum distance where two objects can be clearly distinguished

21
Q

3 types of microscopes

A

Optical light microscope
transmission electron microscope
scanning electron microscope

22
Q

How do optical microscopes work and what is max mag and max resolution

A

light is focused through the objector lens on the bottom through the specimen

light passes through the objective lens to the eyepiece lens to produce an image

Magnification = 1500x

Resolution = 200 nm

23
Q

How do TEMs work and max mag and res

A

electrons pass through specimen

and are focused by electromagnets to produce and image

denser parts absorb more electrons so appear darker

magnification = 500000x

resolution = 0.1 nm

24
Q

Limitations of transmission electron microscopes

A

cant view live specimens as interior is a vacuum

specimen has to be sliced very thinly

requires expensive staining process that can lead to artefacts

25
Q

why is the resolution of electron microscopes higher than light microscopes

A

electrons have a shorter wavelength than light

26
Q

How do SEMs work and max mag and res

A

produce a 3D image as electrons bounce off the specimen and are detected at multiple detectors

magnification = 100,000 x

resolution = 0.1 nm

27
Q

Formula for magnification

A

Mag = image size / actual size

28
Q

How do you measure the actual size of an image through a microscope

A

use a eyepiece graticule and a stage micrometer

  • line up graticule with micrometer
  • count number of graticule divisions that correspond with the stage micrometer
  • calculate distance in micrometres of one division on the graticule
29
Q

What is ultracentrifugation used for and what is the process

A
  • to separate cell components or to get a cell free liquid
  • centrifuge your prepared solution at a low speed (separates nuclei into a pellet at the bottom) to leave a SUPERNATANT LIQUID
  • Re spin the supernatant at a higher speed to separate mitochondria and chloroplasts
  • Keep repeating at higher speeds to separate endoplasmic reticulum and Golgi body and eventually leaves a cell free liquid
30
Q

How do you prepare a solution for ultracentrifugation

A
  • homogenise(squash) cells to break them open
  • place in a COLD, ISOTONIC and BUFFERED solution (prevent enzyme activity which could affect results)(prevents osmosis)
    (prevents pH changes which could denature proteins)
  • Filtered to get rid of cell debris
31
Q

what are artefacts in microscopes

A

excess staining that appear through transmission electron microscopes

32
Q

Stages of the cell cycle

A

Growth 1 (
S phase (DNA replication)
Growth 2 (
(ALL PART OF INTERPHASE)
Mitosis

33
Q

What is mitosis and what is division of the cell

A

A nuclear division

cell division is cytokinesis ( leaves 2 genetically identical daughter cells)

34
Q

Stage 1 of cell cycle

A

Interphase

G1 - proteins are synthesised and cells grow larger
S phase - DNA replication occurs
G2 - additional growth

35
Q

Stage 2 of cell cycle

A

Prophase

Chromatin supercoils so chromosomes condense and become visible

Nuclear envelope breaks down

spindle fibres form

36
Q

Stage 3 of cell cycle

A

Metaphase

chromosomes line up on the equator

spindle fibres attach at the centromere

37
Q

Stage 4 of cell cycle

A

Anaphase

sister chromatids are separated at the centromere

and pulled to opposite poles of the cell by spindle fibres contract

38
Q

Stage 5 of cell cycle

A

Telophase

Nuclei are formed at both poles of the cell

and cytokinesis occurs leaving 2 genet iden daughter cells

39
Q

How do prokaryotes divide

A

binary fission

circular DNA and plasmids are replicated and the cytoplasm divides

BIO PAPER 1 (10 decks)

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