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Biology > 2.2.1 Cell structure > Flashcards

2.2.1 Cell structure Flashcards

1
Q

Name all the structures in a eukaryotic cell

A

Cell-surface membrane
nucleus
mitochrondria
Chloroplasts
gogli apparatus and golgi vesicles
lysosomes
ribosomes
rough endoplasmic reticulum
smooth endoplasmic reticulum
ribosomes
cell wall
cell vacuole

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2
Q

Give the formula to calulate magnification

A

maginification= size of image÷size of real object

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3
Q

Define magnification

A

the number of times bigger the image/ drawing compared to the object /real size

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4
Q

Define cell fractionation

A

The process where cells are broken up and different organelles they contain are seperated out.

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5
Q

Describe what is done to the tissue before cell fractionation occurs

A

Placed in a cold, buffered solution of the same water potential.

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6
Q

Why is the solutuion the tissue is placed in cold?

A

To reduce enzyme activity that might break down the organelles.

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7
Q

Why is the solutuion the tissue is placed in of the same water potential?

A

To prevent organelles bursting or shrinking as a result of osmotic gain or loss of water.

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8
Q

Why is the solutiuon the tissue is placed in buffered?

A

So that pH does not fluctuate. Any cvhanges to pH could alter the structure of the organelles or affect the functioning of enzymes.

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9
Q

Name the 5 structures the nucleus consists

A

Nuclear envelope
Nuclear Pores
Nucloplasm
Chromosomes
Nucleolus

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10
Q

Describe function and structure of nuclear envelope

A

-is a double membrane surrounding the nuclues
-outer membrane is continuous with endoplasmic reticulum
-often had ribosomes on its surface
-controls the entry and exit of materials in and out of nucleus -contains reactions taking place within it

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11
Q

Describe the function of the nuclear pores

A

-Allows the passage of large molecules such as messanger RNA out of the nucleus.

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12
Q

Describe the structure and function of the nucleoplasm

A

The granular, jelly-like material that makes up the bulk of the nucleus.

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13
Q

Describe the structure and function of the nucleolus

A

-A small spherical region within the nucloplasm
-Manufactures ribosomal RNA and assombles the ribosomes
-May be more than one nucleolus

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14
Q

Chromosomes consist of ….

A

Protein bound, Linear DNA

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15
Q

Describe the function of the cell-surface membrane

A

It is selectively permeable so controls passage of substances, it has receptors on its surface allowing cell to cell signalling

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16
Q

Describe the structure of the nucleus

A

It consisters of a nuclear envelope which has a double membrane and pore, inside there is the nucloplasm and the nucleolus which is the dense region, There is also protein bound linear DNA i the forms of condensed chromstion and highly condenses chromosomes

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17
Q

What are ribosomes made of ?

A

Ribosomal RNA and protein (two subnits)

18
Q

Describe the function and structure of rRER

A

Ribosomes on surface synthesise protiens, Proteins are Processes/ folded/ transported into the rER. Proteins packed into vesicles for transport to Golgi appartus

19
Q

Describe the function of the sER

A

It synthesises and processes lipids (e.g cholestral)

20
Q

Describe the stucture of Golgi apparatus and Goldi vesicles

A

Goldi apparatus- Flattened membrane sacs
Golgi Vesicle - Small ,membrane

21
Q

Describe the function of the golgi apparatus

A

It modifies proteins and lipids to produce e.g glycolipids/proteins, It also packages proteins/ .ipids into golgi vesicles
Produces lysosmes

22
Q

Describe the function of the Goldi vesicles

A

They transport proteins/ lipids to their required destination by moving to and fusing with cell- surface membranes

23
Q

Describe the structure of lysosmes

A

Spherical membrane bound organelles that consist of a membrane containing hydrolytic enzymes

24
Q

Describe the function of lysosmes

A

To release hydrolytic enzymes (lysozomes)
To break dow and hydrolyse pathogens or worn oyt cell components

25
Q

Desribe the structure of mitochondria

A

It consists of an outer membrane
Cristae- inner membran fold
Matrix- containing small 70s ribosmes & circular DNA

26
Q

Describe the structure of chloroplasts in plants and algae

A

It is a double membrane with stomata containing:
Thylakoid membrane
small 70s ribosomes
Circular DNA
Starch granuels/ Lipid droplets
It has Lamella- Thykkaloid linking grana
Grana- STacks of thykaloid

27
Q

What is the function of chloroplasts for plants and algae

A

Absorbs light energy for photosynthesis and produes organic substances like carbohydrates and lipids

28
Q

Wat is the cell wall composed of in plants, algae and fungi

A

Composed mainly of cellulose -Plants & Algae
Composed of chitin- Fungi

29
Q

Describe the function of the cell wall in plants, algae and fungi

A

It provude mechanical strength to the cell
This preventds the cell chaging shape or bursting under pressure due to osmosis

30
Q

Describe the structure of the cell vacuole in plants

A

Has a tonoplast membrane and cell sap

31
Q

Describe the function of the cell vacuole in plants

A

It mantains turgor pressure in cell stopping the plant from witling and contains cells sap to store sugars amino acids, pigments and any waste chemicals

32
Q

What are the distinguishing features of prokaryotic cells?

A

Cytoplasm lacking membrane bound organelles so its getic material is not enclosed in a nucleus

33
Q

Desribe the structure of prokaryotic cells

A

Contains cell- surface membran/ cell wall/ cytoplasm/ small ribosomes and circukar DNA always
It sometimes contains Capsule/ Plasmids and Flagella

34
Q

Draw and descrive the general structure of a virus particle

A

Nucleic acids surrounded by a capsid
Attachment proteins allow attachment
to specific host cells
No cytoplasm, ribosomes, cell wall,
cell-surface membrane etc.
Some also surrounded by a lipid
envelope eg. HIV

35
Q

What is resolution?

A

A minimum distance apart 2 objects can be to be distinguished as seperate objects

36
Q

Compare the principles and limitations of optical microscopes, transmission electron microscopes and scanning electron microscopes

A

OP focuses using glass lense, TEM&SEM use electromagnets
OP passes light through specimen and different structure absorb diff wavelength TEM & SEM pass elecrons through specimen so denser parts absorb more and appear darker.
OP & TEM create 2D image of a cross section SEM generates 3D image of a surface
OP has low resolution due to long waveL of light TEM had very high resolution SEM has high resolution both due to short wavelength of electrons
OP cannot see internal structure of orbanelles or ribosomes, TEM can and SEM cannot
OP sepcimen must be thin TEM must be very thin, SEM dont need to be thin
OP can view living organisms, TEM & SEM only dead/ dehydrated in a vacuum
OP low magnification SEM & TEM high magnification
OP can show colour, TEM & SEM cannot show any colour

37
Q

How do you turn mm into um?

A

x1000

38
Q

How to convert micrometre (um) to nanometre?

A

x1000

39
Q

Describe how the size of an object viewed with an optical microscope can be measured

A

You can line up the eyepience graticule with the stage micrometre
Calibrate the eyepiece graticule- use stage micrometre to calculate size of divisions on the eyepiece graticule
Take micrometre away and graticle to measure how many divisions make up the object
Calculate the size of the object by multiplying number of divisions by size of division
Recalibrate eyepiece graticule at different magnifications

40
Q

Describe and explain the priciples in cell fractination and ultracentrifugation as used to seperate cell components

A

The tissue is homogenised using a blender- this dirupts cell membrane, breaking open cells and releasing contents/organelles
It is placed in a cold, isotonic, buffered solution - this reduces enzymic activty so organelles are not damaged- isotonic so water dosent move in and out of cell by osmosis as there is no water potential- Buffered to keep pH constant so enzymes dont denature
Homogenate is filtered- Removes large/ unwanted debris
Ultracentrifugation seperates organelles by density and mass - centrifuge homogenate in a tube at high speed- Removes pellet of heaviest organelle and respin supernatant at a higher speed- Repeat at increasing speed until seperated out

41
Q

What is the order in which organelles are seperated out in ultracentrifugation?

A

Nuclei-Chloroplasts/mitochondria-lysosomes-ER-ribosomes

42
Q

What is importance of fluidity in cell membrane

A

Phagocytosis
vesicles

Biology (9 decks)

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