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A LEVEL BIOLOGY > TOPIC 2.1 Eukaryotic Cells > Flashcards

TOPIC 2.1 Eukaryotic Cells Flashcards

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1
Q

Magnification of light microscopes

A

*1500

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2
Q

magnification of electron microscope

A

*500,000

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3
Q

define resolution

A

A measure of how close together two objects must be before we see them as one.

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4
Q

what do we call an image of an object as viewed through a microscope

A

micrograph

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5
Q

resolving power of light microscope

A

200nm

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6
Q

resolving power of electron microscope

A

0.5 nm

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7
Q

total magnification

A

eyepiece lens magnification*objective lens magnification

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8
Q

strengths and Limitations of Light Microscopes

A

S-
Cheap
can look at live cells with little prep

L-
lower Magnification and resolving power compared to EM

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9
Q

Instead of a beam of light like LM, EM uses a beam of…..

A

electrons

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10
Q

EM has a higher resolving power because the wavelength of electron beams is …..

A

Smaller than LM

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11
Q

Bane 2 types of EMs

A

TEM-transmission electron microscope
SEM- scanning electron microscope (produces 3D images)

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12
Q

Strengths and Limitations of Electron Microscopes

A

S-
high magnification and resolving power

L-
very expensive

specimens have to be examined in a vacuum so they have to be dead and dry

specialised skills required to prepare samples

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13
Q

the nucleus is surrounded by a double membrane called the…

A

nuclear envelope

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14
Q

define nucleolus

A

dense area almost pure DNA and protein, Produces ribosomes and RNA

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15
Q

What are ribosomes made of

A

ribosomal RNA and protein

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16
Q

what is a eukaryotic cell

A

genetic material is contained in a membrane bound nucleus

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17
Q

what are vesicles

A

membrane bags that hold secretions made in cells

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18
Q

what are gated channels

A

protein channels through the lipid bilayer of a membrane that are open or closed depending on the conditions in the cell

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19
Q

describe the fluid mosaic model

A

current model of the structure of the cell membrane including floating proteins forming pores, channels and carrier systems in a lipid bilayer

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20
Q

what is exocytosis

A

energy requiring process by which vesicle fuses with the cell surface membrane so that the contents are released to the outside of the cell

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21
Q

the cytoplasm and nucleus combined are called the…

A

protoplasm

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22
Q

what is chromatin

A

combination of DNA bonded to protein found in the nucleus when the cell is not actively dividing

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23
Q

what do you call the folding of the inner membrane of the mitochondria which provide a large surface area for the reactions of aerobic reactions

A

cristae

24
Q

describe the endosymbiotic theory

A

the endosymbiotic theory–>

theory that suggests the mitochondria and chloroplasts originated as independent prokaryotic organisms that began living symbiotically inside other cells as endosymbionts

25
Q

what are centrioles

A

bundles of tubules found near the nucleus and involved in cell division by the production of a spindle of microtubules that move the chromosomes to the ends of the cell

26
Q

what do you call vacuoles that can fill and empty and why are they important

A

contractile vacuoles, they help control the concentration of cytoplasm of simple freshwater animals

27
Q

purpose of apoptosis ?

A

break down worn out, damaged or diseased cells by lysomes

28
Q

what is a lysome

A

an organelle full of digestive enzymes used to break down worn out cells/ digest food in simple organisms

29
Q

80S ribosomes are made of a small sub unit and a large subunit.. they are…. and the ratio of RNA to protein is

A

80S=40S+60S
RNA:PROTEIN= 1:1

30
Q

70S ribosomes made in the mitochondria are made up of… in the ratio…

A

70S=30S+50S
RNA:PROTEIN= 2:1

31
Q

difference between Necrosis and Apoptosis

A

NECROSIS
-detrimental to body
-triggered when cells are exposed to extreme conditions
-passive random and unregulated

APOPTOSIS
-active and regulated process
-not detrimental to body

32
Q

State the differences between Rough endoplasmic reticulum and Smooth endoplasmic reticulum

A

RER
-ribosomes on surface
- responsible for packing and processing of proteins made by the ribosomes

SER
-no ribosomes
-synthesises lipids, phospholipids and steroids

33
Q

Describe the cell wall of a plant

A

Mostly insoluble cellulose. Freely permeable, it does not act as a barrier for substances entering the cell.

34
Q

How does the cell wall prevent substances from getting into the cell

A

Cell wall can become impregnated with suberin and lignin, affecting permeability

35
Q

the first layer to form when the plant cell divides in 2 is called______ it is made of ________ ___________ that binds the layers of ___________ together.

A

the first layer to form the plant cell divides in 2 is called the middle lamella it is made of calcium pectate that binds the layers of cellulose together

36
Q

state and explain what polysaccharide holds the cells walls of neighbouring plant cells together.

A

PECTIN- pectin has lots of -COOH carboxyl groups that combine with positive calcium ions to form calcium pectate that binds to the cellulose on either side .

37
Q

Why is the primary cell wall flexible

A

the cellulose microfibrils are all orientated towards the same direction

38
Q

When does the secondary cell wall form

A

when the plant ages secondary thickening takes place

39
Q

Difference between primary and secondary walls of plants in terms of flexibility

A

primary Cell wall is flexible as the cellulose microfibrils are all orientated in a similar direction while in the secondary cell wall cellulose microfibrils are laid densely at different angles to each other

40
Q

the______ forms when the cell divides and the 2 cells do not separate fully-leaving cytoplasm bridges between them

A

the plasmodesmata forms when the cell divides and the 2 cells do not separate fully-leaving cytoplasm bridges between them

41
Q

the symplast is…

A

the interconnected cytoplasm of cells. All the material contained within the surface membrane of a plant cell

42
Q

the vacuole is surrounded by a membrane called the ______

A

tonoplast

43
Q

the vacuole is filled with _________ , a substance of various substances in water, which causes water to move into the cell by _______

A

the vacuole is filled with Cell sap , a substance of various substances in water, which causes water to move into the cell by osmosis

44
Q

similarities between chloroplasts and mitochondria

A

large organelles
contain their own DNA
surrounded by an outer membrane
folded inner membrane that gives them large surface areas

45
Q

differences between chloroplasts and mitochondria

A

chloroplast-
site of photosynthesis
contain chlorophyll
are formed from leucoplast

46
Q

what is an amyloplast

A

amyloplasts are plant organelles that store amylopectin (polysaccharide joined with amylose to form starch) which can be converted glucose to provide energy to the cells

47
Q

define tissue

A

a group of specialised cells carrying out a particular function in the body

48
Q

define organ

A

a structure made up of several different types of tissues grouped together to carry out a particular function in the body

49
Q

define an organ system

A

a group of organs working together to carry out particular functions in the body

50
Q

purpose of epithelial tissues

A

form the lining of surfaces inside and outside the body

51
Q

what is the plasmodesmata

A

cytoplasmic bridges between plant cells that allow communication between the cells

52
Q

what is pectin

A

a polysaccharide that holds the cell walls of neighbouring plant cells together and is part of the structure of the primary cell wall

53
Q

____________ is a chemical that impregnates cellulose cell walls in cork tissues and makes them impermeable

A

SUBERIN is a chemical that impregnates cellulose cell walls in cork tissues and makes them impermeable

54
Q

What type of ribosomes do eukaryotic cells have

A

80S—-> 60S and 40S

55
Q

Describe how the electron microscope works

A

An Electron Microscope works by firing a beam of electrons at a biological sample, which then interacts with the sample and produces an image. The electrons are focused into a beam using magnetic lenses and are then directed towards the sample.

A LEVEL BIOLOGY (10 decks)

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