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cells Flashcards

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1
Q

What are the functions of lysosomes?

A
  • hydrolyse phagocytic cells
  • exocytosis - releases enzymes to the outside of the cell to destroy material
  • completely break down dead cells (autolysis)
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2
Q

What are the functions of Golgi Apparatus?

A
  • secrete carbohydrates
  • form lysosomes
  • transport, modify and store lipids
  • add carbohydrates to form glycoproteins
  • produce secretory enzymes
  • molecules are ‘labelled’ with their destination
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3
Q

What are the functions of mitochondria?

A
  • site of ATP production
  • site of aerobic respiration
  • has the DNA that codes for the enzymes needed for respiration
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4
Q

What are the functions of a nucleus?

A
  • site of DNA replication and transcription (making mRNA)
  • contains the genetic code for each cell
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5
Q

What are the functions of the SER?

A
  • synthesis
  • stores lipids and carbohydrates
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6
Q

What are the two types of electron microscopes?

A
  • scanning electron microscope (SEM)
  • transmitting electron microscope (TEM)
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7
Q

What is the formula for magnification?

A

magnification = size of image / size of object

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8
Q

What are the features of an SEM?

A
  • SEMs knock electrons off the specimen and these electrons come together to form an image
  • SEM images can be three-dimensional
  • Specimens do NOT have to be thin like when using a TEM
  • Resolution is lower than that produced by a TEM
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9
Q

What are the features of a TEM?

A
  • TEMs use electromagnets to focus the electron beam
  • TEMs are high resolution microscopes
  • in thin specimens, you can see the internal structures of organelles such as chloroplasts
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10
Q

What is meant by ‘membrane-bound organelle’?

A

an organelle that is surrounded by a phospholipid layer

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11
Q

Examples of membrane bound organelles

A
  • mitochondria
  • endoplasmic reticulum (SER and RER)
  • chloroplasts
  • lysosomes
  • nucleoli & nuclei
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12
Q

Examples of non-membrane bound organelles

A
  • ribosomes
  • cytoskeleton
  • centrioles
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13
Q

What is meant by magnification?

A

how many times bigger the image is compared to the object

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14
Q

What is meant by resolution?

A

the minimum distance that objects can be in order for them to appear as separate things

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15
Q

Why is a solution cold in homogenisation?

A

so the the rate of enzyme (lysosyme) activity is decreased

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16
Q

Why is a solution buffered in homogenisation?

A

it maintains a constant pH so it does not denature proteins

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17
Q

Why is a solution isotonic in homogenisation?

A

has the same water potential as the tissue so no net movement of water by osmosis, so this prevents cell lysis

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18
Q

What are ribosomes made of?

A
  • ribosomal RNA and proteins
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19
Q

What is the maximum resolution of an optical microscope?

A

0.2um

20
Q

What is the maximum magnification of an optical microscope?

A

x1,500

21
Q

What is the maximum magnification of a TEM?

A

x500,000

22
Q

What is the maximum resolution of a TEM?

A

0.0001um

23
Q

Limitations of EMs (in general)

A
  • can’t view live specimens/process due to the interior of the microscope being in a vacuum
  • specimen has to be sliced very thinly
  • requires an extensive staining process that can lead to artefacts
24
Q

Features of an SEM

A
  • produces 3D image
  • electrons BOUNCE OFF specimen and are detected at multiple detectors
25
Q

What is the maximum resolution of an SEM?

A

0.0001um

26
Q

What is the maximum magnification of an SEM?

A

x100,000

27
Q

What are the 3 stages of interphase?

A
  • G1
  • S
  • G2
28
Q

What happens in the G1 phase?

A

the cell grows and makes a new set of organelles and proteins for the daughter cells

29
Q

What happens in the S
phase?

A
  • the DNA in the cell is replicated, so that the two daughter cells can each get one set of DNA
  • also a checking of genetic material in this phase
  • summary: synthesis of new DNA
30
Q

What happens in the G2 phase?

A
  • cell growth continues
  • synthesis of special proteins in preparation for mitosis
31
Q

What is mitosis necessary for?

A
  • growth
  • replacing/repairing cells
  • asexual reproduction
32
Q

What are the stages of mitosis?

A
  • Prophase
  • Metaphase
  • Anaphase
  • Telophase
33
Q

What happens during prophase?

A
  • chromosomes condense and are now visible when stained
  • nuclear envelope breaks down
  • nucleolus disappears
34
Q

What happens during metaphase?

A
  • chromosomes line up at the equator of the cell
  • spindle fibres reach the chromosomes and attach to the centromeres
  • each sister chromatid is attached to a spindle fibre
35
Q

What happens during anaphase?

A
  • the sister chromatids separate at the centromere
  • spindle fibres begin to shorten
  • the separated sister chromatids (now called chromosomes) are pulled to opposite poles by the spindle fibres
36
Q

What do prokaryotes have instead of mitochondria?

A

mesosomes - attach to cell membrane

37
Q

What are the functions of glycoproteins?

A
  • acts as recognition sites
  • help cells attach to one another + form tissues
38
Q

why are phospholipids present in cell membranes

A

they form a stable barrier that regulates what enters and exits the cell

39
Q

why are proteins present in cell membranes

A
  • cell-cell recognition
  • selective transport
  • structural support
40
Q

why are glycoproteins present in cell membranes a level biology

A
  • cell-cell recognition (helps recognise antigens from pathogens)
  • cell adhesion (helps form tissues and provide structural integrity)
  • cell signalling (act as receptors that receive signals from hormones and neurotransmitters, and relay these signals to the inside of the cell)
41
Q

what is facilitated diffusion

A

net movement of large polar molecules or ions moving from area of high conc. to area low conc. using carrier proteins and protein channels

42
Q

what is simple diffusion

A

Simple Diffusion is the net movement of particles down a concentration gradient, from a high concentration to low concentration.

43
Q

the two types of diffusion are?

A
  • simple
  • facilitated
44
Q

what is osmosis

A

the passage of water from a region where it has a higher water potential to a region where it has lower water potential down the water potential gradient through a selectively permeable membrane

45
Q

what does cholesterol do for the cell surface membrane?

A
  • restricts lateral movement of other molecules
  • makes membrane less fluid at high temperatures
  • prevents leakage of water and dissolved ions from the cell
46
Q

why are glycolipids present in the cell surafce membrane

A

Biology (8 decks)

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