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biology year 12 > topic two > Flashcards

topic two Flashcards

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1
Q

cell surface membrane

A
  • made of lipids and proteins
  • regulates movement of substances in and out of the cell/has receptor molecules on it which allow it to respond to hormones.
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2
Q

nucleus

A
  • surrounded by nuclear envelope which contains pores. pores allow RNA to move between cytoplasm.
    -chromatin consists of DNA RNA and proteins. nucleolus consists of DNA RNA and proteins too
  • controls cells activities by controlling DNA transcription/ controls gene expression, protein synthesis and storing DNA.
    ribosome production and protein synthesis in nucleolus.
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3
Q

mitochondria

A
  • oval shaped structure with outer and inner membranes. inner is folded to form cristae and inside is called matrix which contains enzymes for respiration
  • site of aerobic respiration, releases energy
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4
Q

chloroplast

A
  • have a double membrane that surrounds the stoma. inside the stoma there is fluid filled sacs called thylakoids.
  • site of photosynthesis; light independent reactions in sacs, light dependent reactions in stoma
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5
Q

golgi apparatus

A
  • composed of small vesicles, a membrane bound structure filled with fluid
  • processes and packages lipids & makes lysosomes
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6
Q

lysosome

A
  • surrounded by a membrane with no clear internal structure.
  • contains lysozyme, kept separate from cytoplasm by surrounding membrane, used to digest invading cells
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7
Q

ribosome

A
  • floats free in cytoplasm/or attached to RER, made of proteins and RNA
  • site where proteins are made
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8
Q

rough endoplasmic reticulum

A
  • system of membranes enclosing a fluid filled space, surface covered with ribosomes
  • folds/processes proteins made at ribosome
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9
Q

smooth endoplasmic reticulum

A
  • no ribosomes, but similar to RER
  • synthesises and processes lipids
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10
Q

cell wall

A
  • rigid, surrounds membrane. cellulose in plants and chitin in fungi
  • supports cells, protection against pathogens
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11
Q

vacuole

A
  • membrane bound (called the tonoplast), contains cell sap (solution of sugars and salts)
    -maintains osmotic pressure, stops plants wilting, stores unwanted chemicals
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12
Q

differences between prokaryotic compared to eukaryotic

A
  • cytoplasm has-no bound organelles
  • no nucleus, circular DNA instead
  • plasmids
  • capsule surrounding the cell
  • flagellum
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13
Q

structure of virus particles

A
  • genetic material surrounded by capsid
  • lipid envelope with attachment proteins
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14
Q

formula for magnification

A

image = actual size x mag

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15
Q

how high can a light microscope measure resolution

A

0.2 micro metres

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16
Q

why can light microscopes only measure a small amount of resolution

A

the microscope cant produce the image of an object that is smaller than the wavelength of light

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17
Q

how high can an electron microscope measure resolution to

A

0.1 nm

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18
Q

what are the two types of electron microscopes

A
  • scanning electron microscope
  • transmission electron microscope
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19
Q

how do TEMs work

A

a beam of electrons passes through a thin piece of the specimen.
areas that absorb electrons appear darker

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20
Q

how do SEMs work

A

a beam of electrons passes across the surface and scatters.
this builds up a 3D image

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21
Q

limitations of SEMs

A
  • lower resolution
  • specimens have to be dead
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22
Q

strength of SEMs

A
  • can produce 3D images
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23
Q

limitations of TEMs

A
  • samples need lots of prep
  • very expensive
  • cant produce 3D images
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24
Q

strengths of TEMs

A
  • high resolution
    specimens can be alive
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25
Q

what is cell fractionation

A

separating cells and organelles to study them in detail

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26
Q

explain homogenisation

A
  • cells are blended in a homogensier to form a fluid called homogenate.
  • this is added to a centrifuge
  • the heaviest organelles are forced to the bottom where a sediment forms (lowest speed)
  • the fluid at the top is called the supernatant, this is removed and added to a different tube
  • the supernatant is then spun at higher speeds to force the smaller organelles
  • the last organelle to be forced to the bottom is ribsomes.
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27
Q

why is the solution ice cold

A

to stop the organisms from breaking down organelles

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28
Q

why is a buffer solution used

A

to maintain pH

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29
Q

why is an isotonic solution used

A

to prevent bursting and shrinking

30
Q

what is mitosis for

A
  • division of cells for growth and repair and reproduction
31
Q

how many cells does mitosis produce

A

2 genetically identical daughter cells

32
Q

what are the three stages of the cell cycle

A
  • interphase
  • mitosis
  • cytokinesis
33
Q

what are the four stages of mitosis

A
  • prophase
  • metaphase
  • anaphase
  • telophase
34
Q

what happens during interphase

A

the cell grows and prepares to divide

35
Q

what happens during cytokinesis

A

the organelles moves to opposite ends of the cell and the cytoplasm divides to form 2 separate cells

36
Q

prophase

A
  • chromosomes condense
  • spindle fibres appear
  • nuclear membrane breaks down
37
Q

metaphase

A
  • chromosomes align
38
Q

anaphase

A
  • sister chromatids move to opposite poles
  • centrometers divide
39
Q

telophase

A
  • nuclear membrane reforms
  • spindle fibres disappear
  • chromosomes decondense
40
Q

what is the process by which prokaryotic cells divide called

A

binary fission

41
Q

steps of binary fission

A
  • circular DNA replicates and attach to the cell membrane, plasmids also replicate
  • cell membrane begins to grow inbetween the DNA molecules and pinches inwarsd to form 2 cells
  • a new cell wall forms between the two divided DNA molecules
  • the identical daughter cells both have a copy of circular DNA and mulitple copies of the plasmids
42
Q

why do viruses not replicate

A

the are not living

43
Q

what happens after a viruses injection of nucleic acids

A

the infected host cell replicates the virus particles

44
Q

what do receptors on cell membranes allow molecules to do

A

enables adjacent cells to stick together

45
Q

why is was it given the name ‘fluid mosaic model’

A

the fluidity of the membrane and the arrangement of the proteins

46
Q

how do the hydrophil/phobic heads and tails point

A
  • hydrophilic head = points outwards
  • hydrophobic tail = points inwards
47
Q

why do the head and tail point these ways

A
  • allows lipid soluble substances to pass through, but not water soluble
  • means membrane is flexible and self-sealing
48
Q

what are the two types of proteins in the cell membrane

A
  • intrinsic = throughout the membrane
  • extrinsic = along the surface
49
Q

what is the function of intrinsic proteins (carrier proteins)

A
  • carriers = allow substances to cross the membrane
  • provide mechanical support
  • act with glycolipds as receptors
50
Q

what is the function of cholesterol in the membrane

A
  • makes the membrane more rigid and reduces movement of phospholipids
  • prevents leakage of water and dissolved ions, since it is hydrophobic
51
Q

what are glycolipids made of

A

a carbohydrate that is bound to lipids

52
Q

what is the function of glycolipids in the membrane

A
  • act as cell surface receptors for certain substances
  • allow cells to adhere together to form tissues
53
Q

what are glycoproteins made from

A

carbohydrates attached to extrinsic proteins

54
Q

what is the function of glycoproteins in the membrane

A
  • act as cell surface receptors and neurotransmitters
  • also allow cells to adhere together to form tissues
55
Q

what is diffusion

A

passive movement of small non polar molecules from an area of high conc. to an area of low conc.
molecules move through the phospholipid bilayer

56
Q

what is osmosis

A

diffusion of water molecules from an area of high conc. to an area of low conc. through a partially permeable membrane

57
Q

what is facilitated diffusion

A

requires channel proteins in membrane to transport water soluble and polar molecules

58
Q

what is active transport

A

transports all types of molecules through carrier proteins, from an area of low conc. to an area of high conc. requires lots of ATP

59
Q

exocytosis and endocytosis

A
  • transport large molecules
60
Q

what happens in endocytosis

A

particles are enclosed in vesicles and transported into the cell

61
Q

what happens in exocytosis

A

the vesicles containing large particles are fused with the cell membrane and released into the cell

62
Q

what is co transport

A

uses ions to moe substances in and out of the cell

63
Q

where does co transport occur

A

epithelial cells of the ileum

64
Q

what happens during co transport

A

sodium and potassium ions are pumped out of the epithelial cells by AT, into the blood which leaves a lower concentration in the cell. this causes these ions to move in by facilitated diffusion which brings glucose and amino acids into the cell. thse then diffuse from high conc in epithelial to low conc in blood.

65
Q

DNA in bacteria and prokaryotes

A
  • circular
  • short
66
Q

DNA in viruses

A
  • consist of only nucleic acid in a protein coat
  • can take the form of DNA or RNA
67
Q

what cell do viruses require

A

host cell

68
Q

what do viruses not have

A
  • organelles
69
Q

examples of bacterial infections

A
  • TB
  • whooping cough
  • strep throat
70
Q

example of viral infection

A
  • HIV
  • common cold/flu
  • covid-19
  • bronchitis
71
Q
A

biology year 12 (5 decks)

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