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Biology - B, Y12 > Cells -B5 > Flashcards

Cells -B5 Flashcards

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1
Q

What does ATP consist of and what is it used for?

A

ATP consists of a nitrogenous organic base and three phosphate groups and is used as the energy source in plants and animals to carry out essential life processes.

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1
Q

What is endosymbiosis?

A

Cells engulfing each other for a mutual benefit

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2
Q

How is ATP produced?

A

ATP is produced by joining ADP(adenosine diphosphate) and inorganic phosphate.

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3
Q

Why is ATP hydrolysed?

A

ATP is hydrolysed to provide energy for cell reactions i.e. active transport, muscle contraction, and protein synthesis.

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4
Q

What is the journey of a protein?

A

-nucleus: DNA codes for mRNA(protein) > RER: proteinsynthesis - ribosomes(in vesicle) > Golgi : package, identify, modify the protein > exocytosis - leave cell > vesicle breaks down +protein released
-mitochondria - ATP - protein synthesis, vesicle and transportation

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5
Q

What are the sub-cellular structures of an epithelial cell?

A

1)mitochondria
2)cell membrane
3)cytoplasm
4)ribosomes
5)rough endoplasmic reticulum
6)golgi apparatus
7)smooth endoplasmic reticulum
8)lysosomes
9)nuclear envelope/membrane
10)nucleus
11)chromatin
12)centrioles/centrazone
13)microtubules

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6
Q

What happens in the mitochondria?

A

-where aerobic respiration takes place. they have a double membrane.
-ATP is formed in the mitochondria - respiration
-inner membrane forms cristae
-matrix> contains enzymes - outer membrane
-have their own DNA due to endosymbiosis

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7
Q

What happens in the ribosomes?

A

-small structures which are found in cytoplasm and RER
-contain ribosomal RNA
-size: 80s. -eukayotic, 70s. prokaryotic
-function: carry out proteinsynthesis

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8
Q

What happens in the RER?

A

-transports proteins throughout the cell
-has ribosomes on outer surface(proteinsynthesis)
-cells which makes lots of proteins have lots of RER
-cisternae and ribosomes

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9
Q

What happens in the golgi apparatus?

A

-sorts, modifies and packages molecules, such as proteins produced by the cell, into vesicles(may be used to form lysosomes)
-composed of flattened cysternae sacs made of membranes. The sacs are fluid filled and pinch off vesicles at their ends.
-usually only one golgi body in each cells, as large molecules must be packaged in vesicle to be transported out of cell.
-sort, label, and package proteins

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10
Q

What happens in the SER?

A

-function: synthesises lipids, carbohydrates and steroids.
-no ribosomes on outer surfaces
-cisternae and flat sacs

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11
Q

What happens in lysosomes?

A

-used to breakdown unwanted structures within the cell
-similar in size to mitochondria. They are bound by a single membrane and have no internal structure.
-contain a large no. of hydrolytic enzymes, which must be kept separate from rest of cell contents to avoid damage
-digestive enzymes

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12
Q

What happens in the nuclear envelope?

A

-let mRNA through

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13
Q

What happens in the nucleus?

A

-production of mRNA
-hereditory information
-retain genetic material in the form of DNA

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14
Q

What happens in the microtubles?

A

-provides structure for cell
-used for transportation

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15
Q

What are the centrioles?

A

Hollow tubes made of microtubules.

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16
Q

What is chromatin?

A

A mixture of DNA and proteins that form the chromosomes found in the cells of humans and other higher organisms.

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17
Q

What is the nucleolus?

A

Small areas within the nucleus where ribosomes are made.

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18
Q

What is the nuclear membrane?

A

Perforated by nuclear pores to allow the exit of mRNA.
holes mRNA can fit, DNA doesn’t.

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19
Q

What is the function of the lysosomes?

A

Used to breakdown unwanted structures within the cell.

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20
Q

What is the smooth endoplasmic reticulum?

A

A system of membranes lacking adjoining ribosomes which synthesises lipids and carbohydrates.

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21
Q

What is the function of the cytoskeleton?

A

A structure that helps cells maintain their shape and internal organisation.
-It’s everywhere(not in images)

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22
Q

What is the function of mitochondria?

A

The site of ATP formation by aerobic respiration.

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23
Q

What is the cell membrane?

A

The outer barrier of the cell made of a phospholipid bilayer.

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24
Q

What are the ribosomes?

A

Small structures made up from two subunits which are used to synthesise proteins.

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25
Q

What is the rough endoplasmic reticulum?

A

A system of membranes with attached ribosomes which synthesises many of the cells’ proteins.

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26
Q

What is the golgi apparatus?

A

System of flattened membranes that processes, modifies and packages molecules, such as proteins and lipids, into vesicles for transport.

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27
Q

What are the sub-cellular structures of bacteria, and what is their function?

A

-cell wall: physical barrier that protects against mechanical damage
-capsule(slime): protects bacteria from other cells and helps groups of bacteria stick together for protection
-cell surface membrane: acts as a partially permeable membrane
-flagellum: aids movement due to it’s rigid corkscrew shape and rotating base to help the cell spin through fluids.
-circular DNA: genetic information for the replication of bacterial cells
-plasmid: posses genetic genes that aid the survival of bacteria
-ribosomes(70s size-they’re smaller)
-nucleoid: circular DNA
-cell wall: made from peptidoglycan
-capsule: slime allows to stick to surfaces- stops from drying out
-pili: (pilus) allow to attatch to other bacteria- surfaces

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28
Q

What is the replication of bacteria called?

A

Binary fission

29
Q

What are the steps in the process of binary fission?

A

1) DNA and plasmids from the parent cell replicate and duplicate
2)the cytoplasm splits/ divides into two daughter cells

-the no. of plasmids each daughter cell gets is random
-“daughter cells” > not genetically identical

30
Q

How much smaller are viruses than animal and bacterial cells?

A

-on average, 10x smaller than animal cells, 100x smaller than bacterial cells > significantly smaller

31
Q

Why are viruses unable to replicate independently?

A

They have no organelles. They require a living cell to replicate inside.

32
Q

Viruses are acellular. What does this mean?

A

They are not living things.

33
Q

What is the structure of a virus, and what are it’s subcellular structures?

A

For all viruses:
-protein capsid
-DNA/RNA : one or another, not both. Single or double stranded.

For some viruses:
-receptors: to bind and enter cells
-nuclear envelope(from a cell)
-reverse transcriptase : enzyme.

34
Q

What is the function of chloroplasts?

A

contains chlorophyll which absorbs light/where photosynthesis occurs.

35
Q

Why do chloroplasts have their own DNA ?

A

They used to be prokaryotic

36
Q

What are the sub-cellular structures in a chloroplasts?

A

Thylakoids discs, stroma, granum

37
Q

What is the function of thylakoids discs?

A

In stacks, they have chlorophyll and absorb light

38
Q

What is the function of the stroma?

A

It’s the liquid found within thylakoid discs, enzymes, light independent reaction.

39
Q

What is the granum?

A

Used for light dependent reactions

40
Q

What is cell fractionation?

A

the separation of cell organelles

41
Q

What are the three stages of cell fractionation?

A

1)homogenization
2)filtration
3)ultracentrification

42
Q

What is homogenisation?

A

-blend/break up cells
-release organelles from cells by breaking plasma membrane
-this can be done either by vibrating the cells or grinding the cells in a blender which breaks the plasma membrane
-solution its done in must be cold, isotonic, and have a buffered pH

43
Q

Why must the solution be cold in homogenisation?

A

to reduce enzyme activity(which could break down cells)

44
Q

Why must the solution be a buffered pH in homogenisation?

A

resist pH change and prevent enzymes denaturing

45
Q

Why must the solution be isotonic in homogenisation?

A

stops osmotic effects(bursting)
-no osmosis
-water potential is even
-no movement of water

46
Q

Why is the solution filtered in cell fractionation?

A

-to remove cell debris and tissue and any complete cells(not broken up)
-cell debris and unbroken cells are removed

47
Q

What is ultracentrifugation?

A

spun at low speed in a centrifuge, heaviest organelles to the bottom
-add supernatant and then spun at a faster and longer so smaller organelles go to the bottom
-then again for smaller organelles
-centrifuge has to be balanced
-heaviest thing falls to the bottom first
-remove supernatant each time, place in new test tube, leaving oher organelles there
-spin faster > next heaviest

48
Q

What is supernatant?

A

liquid containing other organelles

49
Q

What is the order of density cell structures are separated by in cell fractionation?

A

cell wall
nucleus
chloroplast
mitochondria
ribosomes

50
Q

Define magnification.

A

How much bigger you’re making the image/sample -> making things bigger

51
Q

Define resoution.

A

the ability to distinguish between two separate points close together

52
Q

With light microscopes, can specimens be living or dead?

A

specimens can be both, but often need to stained.
Specimens are illuminated with light

53
Q

What is the magnification limited to on a light microscope?

A

The mag. is limited to x1500. This allows individual cells and some large structures to be observed, but none of the smaller structures

54
Q

Why does light have a poorer resolution?

A

light has a poorer resolution as it has a longer wavelength - the wavelength is longer than the sample

55
Q

How do electrons increase resolution?

A

electrons are used to increase resolution as they have a much shorter wavelength than light so have a higher resolution

56
Q

What do electron microscopes use instead of light?

A

uses a beam of electrons to produce an image instead of light

57
Q

What does a vacuum pump do in an electron microscope?

A

a vacuum pump removes all air to stop air molecules getting in the way of the beam of electrons

58
Q

What is the benefit of electrons being negatively charged?

A

the beam can be focused using electromagnets

59
Q

What are the advantages of using electron microscopes?

A

-higher resolution
-higher magnification
-shorter wavelength

60
Q

What are the disadvantages of using electron microscopes?

A

-can’t look at living cells
-must be in a vacuum
-no colour images
-specimens must be thin
-artefacts may end up in the image

61
Q

What is a transmission electron microscope used for?

A

mainly used for studying the internal structures of a cell(2D)

62
Q

What is a scanning electron microscope mainly used for?

A

mainly used to study the surface of cells(3D)

63
Q

What are the advantages of transmission electron microscopes?

A

-higher resolution
-see internal structures

64
Q

What are the disadvantages of transmission electron microscopes?

A

-only see samples in 2D
-samples must be thin

65
Q

What are the advantages of scanning electron microscopes?

A

-can see in 3D
-can see the surface

66
Q

What are the disadvantages of scanning electron microscopes?

A

-poorer resolution

67
Q

What are the limitations of light microscopes?

A

poor resolution(long wavelength)

68
Q

What is the equation for magnification?

A

magnification= image size/actual size

69
Q

What do you do when converting from big units to small units?

A

multiply

70
Q

What do you do when converting from small units to big units?

A

divide

Biology - B, Y12 (9 decks)

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