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A level Biology (Edmond)year 12 > CELLS-cell Structure > Flashcards

CELLS-cell Structure Flashcards

1
Q

What is a carrier molecule (carrier protein)?

A

A protein on the surface of a cell that helps to transport molecules and ions across a plasma membrane

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2
Q

define chromatid?

A

one of the two copies of a chromosome that joined together by a single centromere prior to cell division

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3
Q

define glycoprotein?

A

substance made up of a carbohydrate molecule and a protein molecule

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4
Q

what is Granum?

A

A stack of thylakoids in a chloroplast that resembles a pile of coins, this is the site of the light-dependent reaction of photosynthesis

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5
Q

What does (HDL) stand for and what is it?

A

High-density lipoprotein, it is a compound of protein and lipid molecules found in blood plasma, it transports cholesterol from other cells to the liver.

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6
Q

hydrogen bonds?

A

chemical bond formed between the positive charge on a hydron and a negative charge on another atom of an adjacent molecule

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7
Q

what are intrinsic proteins?

A

proteins of the cell-surface membrane that completely span the phospholipid bilayer from one side to the other

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8
Q

what is a isotonic solution?

A

solution with same conc of solutes and so same water potential

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9
Q

'’in vitro’’ what does this refer to?

A

Refers to experiments carried out outside the living body e.g. test tubes

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10
Q

'’in vivo’’ what does this refer to?

A

refers to experiments that are carried out within living bodies

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11
Q

define and what does it do? (LDL)

A

low-density lipoprotein, A compound containing both protein and lipid molecules that occur in blood plasma and lymph, it carries cholesterol from the liver to other cells in the body.

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12
Q

describe the structure of the Nucleus (largest organelle)?

A

-the nucleus has a nuclear envelope it is a double membrane with nuclear pores to allow movement of mRNA.
-it has a Nucleoplasm full of chromatin
-it has a Nucleolus (dark-centre) -makes the ribosomes

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13
Q

tell me the function of a nucleus?

A

it controls the cells activities by controlling transcription of DNA.
When the cells is not dividing the DNA is bonded to proteins to form chromatin.
When the cell is dividing the DNA exists as chromosomes.

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14
Q

What and describe the role of the rough endoplasmic reticulum (RER)?

A

-series of interconnected flattened sacs
-ribosomes are attached (appear as dark blobs)
-role is the folding and processing of proteins

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15
Q

What and describe the role of the smooth endoplasmic reticulum (SER)?

A

-Tubular structure
-involved in lipid synthesis and processing ‘‘smooth’’ because it doesn’t contain ribosomes

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16
Q

What the mitochondrion have (structure)?

A

-Matrix (cytoplasm)
-ribosomes
-mitochondrial DNA
-ATPase enzyme, enzyme used for respiration. folding on cristae means larger S.A for these to be attached
-cristae (inner folds)
-outer membrane
-

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17
Q

describe the role of the Golgi apparatus/body ?

A

-Takes proteins from RER and lipids from SER to process and package them.
The processed molecules are then bud of in vesicles either used in the cell or leave by exocytosis.

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18
Q

Describe the process of exocytosis?

A

-vesicles pinch of the RER and fuse to form flattened sacs
-(in Golgi apparatus) the stack of flattened cisternae lined with smooth endoplasmic reticulum
-vesicles containing secretions are pinched off the Golgi apparatus
-vesicles fuse with the cell surface membrane and release the secretions.

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19
Q

where and in what form are centrioles located in the cell?

A

normally a pair of centrioles near the nucleus

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20
Q

what are centrioles made up of?

A

made from a bundle of tubules

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21
Q

what is the role of centrioles?

A

-involved in cell division
-when cells divide the centrioles produce a spindle of microtubules which help to pull chromosomes apart

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22
Q

are vacuoles permanent in animal cells?

A

no but is actually formed and lost when needed

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23
Q

where are contractile vacuoles found ?

A

in simple animals that live in water

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24
Q

what are lysosomes?

A

spherical sacs containing digestive enzymes

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25
Q

describe the process of endocytosis?

A

-waste material fuses with cell membrane and is taken in,
-membrane lined vesicles is produced
-then the lysosomes will fuse with the membrane bound vesicles the digestive enzyme in the lysosomes will destroy it.

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26
Q

what are the 2 types of ribosomes called?

A

80s and 70s ribosomes

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27
Q

role of ribosomes?

A

is where protein synthesis occurs

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28
Q

what are ribosomes made from?

A

from ribosomal RNA and protein (ratio of RNA to protein is 1:1)(for 80s )
has a large and small subunit

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29
Q

when 80s ribosomes are broken down it is made from what?

A

40s small subunits and 60s large subunit.

30
Q

describe the structure of a cytoskeleton?

A

-is dynamic (flexible)
-3D-web structure that fills the cytoplasm
-made from microfilaments which is a protein fibre and microtubules
-made from protein called tubulins

31
Q

80s ribosomes a usually found in what type of cell?

A

Eukaryotic cells

32
Q

70s ribosomes have been found where? (usually fond in prokaryotic cells)

A

-mitochondria
-chloroplast of plant cells

33
Q

when 70s ribosomes are broken down it is made from what?

A

made from small 30s subunits and large 50s subunits
ratio of RNA to protein is 2:1

34
Q

what is the function of cytoskeleton?

A

-gives cytoplasm structure- keeps organelles in place
-to move cells/transport substances through it.

35
Q

what are the properties of a plant cell wall?

A

cell walls has insoluble polysaccharide cellulose
-cell wall is freely permeable (so everything dissolves in water)

36
Q

some cell walls can be impregnated with lignin to form wood? (true/false)

A

true

37
Q

the plant cells have a glue that holds walls of cells together what is that glue called?

A

pectin
because negatively charged carboxyl groups binds to calcium to form calcium pectate, this binds to cellulose on either side.

38
Q

the cell wall layer description?
-middle lamella
-primary wall
-secondary wall

A

Middle lamella

Made of pectin. Acts as glue holding cell together. Forms calcium pectate which binds to cellulose on either side.

Primary wall

Made of microfibrils and matrix built up on either side of the lamella. Microfibrils in the same direction so very flexible.

Secondary wall

Microfibrils lie at different angles as the cell ages. Makes the material much more rigid. Lignin can be added to make wood. Long heavily lignified cells are known as plant fibres.

39
Q

what is plasmodesmata?

A

when strands of cytoplasm stretch between cells

40
Q

Name three structures in the chloroplast? (what does it do)

A

-Granum, stack of thylakoids held together by intergranal lamellae
-stroma, produces glucose
-thylakoids, holds chloroplast (absorbs light)

41
Q

What is capsule/slime layer on bacteria made from?

A

Formed from starch, gelatin, protein or glycolipid

42
Q

what is the purpose of a capsule/slime layer?

A

Protects bacteria from phagocytosis and may cover antigens on bacteria surface, making it harder for them to be identified by the immune system (e.g. bacteria that cause pneumonia and TB).

Helps prevent desiccation (drying out), so enables bacteria to survive in dry conditions.

43
Q

what does desiccation mean?

A

drying out

44
Q

what is flagella made from?

A

Made of the protein ‘flagellin’.

45
Q

what is the purpose of the flagella?

A

Rotates rapidly to move bacteria.

46
Q

in cell surface membrane of prokaryotic cells it is a site of what type of enzyme?

A

respiratory enzymes

47
Q

in some bacteria the cell membrane has infoldings called?

A

mesosomes

48
Q

bacteria don’t have a membrane bound nucleus instead they have a single length of DNA which coiled and folded to form the ?

A

Nucleoid

49
Q

What are plasmids?

A

smaller circles of DNA which can reproduce independently of the nucleoid

50
Q

all bacteria cell walls consists of a layer of ?

A

peptidoglycan

51
Q

Describe the process of binary Fission of prokaryotes?

A

1.DNA/Plasmids are replicated (plasma may be copied many times)
2.cell elongation, DNA migrates to poles
3.cytoplasm begins to divide new cell wall starts to form
4.2 daughter cells with identical circular DNA but may have different plasmids.

52
Q

Define magnification?

A

magnification is how many times bigger an image appears

53
Q

define resolution?

A

the ability to determine between two separate points

54
Q

what is the magnification equation?

A

I/AM

55
Q

why does the light microscope have a lover magnification/resolution than a electron microscope?

A

the long wavelength of light rays

56
Q

what is the resolution up to for a electron microscope?

A

0.1nm

57
Q

what are the two types of electron microscopes?

A

-scanning electron microscope
-transmission electron microscope

58
Q

describe the process of a scanning electron microscope?

A

specimens are coated with a thin layer of metal such as gold/platinum/tungsten to improve conductivity and contrast

electrons are reflected to create a 3D image

59
Q

describe the process of a Transmission electron microscope?

A

-very thin slices are made-stained with heavy metals
-electrons don’t pass through but are absorbed instead
-those that pass through are focused by electromagnets onto a fluorescent screen or photographic plate
-allowing us to see inside cells (2D cross sections)

60
Q

what are the pros and cons of a light microscope?

A

pros-cheaper to use than a electron microscope
cons-lower magnification/resolution than electron microscope

61
Q

what are the pros and cons of a transmission electron microscope?

A

pro-provides detailed 2D images inside cells
con-cells stained with heavy or dense metals like osmium (expensive)

62
Q

what are the pros and cons of a scanning electron microscope?

A

pro-creates detailed 3D image of the surface of tissues
con-the specimen needs to be coated in metal like gold to reflect electron (expensive)

63
Q

give me the steps for a eye piece graticule calibration calculation?

A
  1. num of stage divs x 1 division length =ans
  2. 1 eye piece division =ans dive num of eye peice divs
  3. ans x 1000= and in micrometres
64
Q

what is cell fractionation?

A

Cell fractionation is a process where cells are broken up to release the different organelles they contain and they are separated out based on their size/masss using gravity.

65
Q

homogenisation can be done in two ways?

A

-vibrating cells
-grinding them in a blender

66
Q

to be homogenised the solution needs to be in 3 conditions what are those conditions and why are those specific conditions needed?

A

-ice cold solution so the enzymes don’t break down the organelles (slows the rate of enzyme activity)
-need to be a buffer solution to maintain the PH so the organelles don’t change shape
-solution must be isotonic to prevent bursting through osmosis

67
Q

What is centrifugation?

A

A centrifuge uses gravity to separate substances by their weight.
The faster the spinning the faster the G force.
At slower speeds larger fragments collect at the bottom of the tube and smaller ones remain suspended in the liquid

68
Q

what a solution is centrifuged what is the liquid and solid bit in the tube?

A

liquid-supernatant
solid-pellet

69
Q

what is the Organelle Separation Order when you centrifuge?

A

1.Nuclei
Chloroplast
Mitochondria
Lysosomes
Endoplasmic reticulum
Ribosomes

70
Q

Describe the process of cell fractionation?

A
  1. Tissue is cut up and is kept in a cold, isotonic buffered solution
    2.cut up tissue is further broken up in a homogeniser (blender)
    3.Homogenised tissue is spun in a centrifuge at low speed
    4.result of being spun at low speed
    5.then spun at medium speed
    6.spun at high speeds

A level Biology (Edmond)year 12 (4 decks)

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