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Biology > 2.1 Cell Structure > Flashcards

2.1 Cell Structure Flashcards

1
Q

What is a microscope? And what do they allow you to see,?

A
  • it’s an instrument which allows you to magnify an object hundreds, thousands and even hundreds of thousands of times
  • allow to see many unicelular organisms
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2
Q

Due to microscopes… what does the cell theory state?

A
  • both plant and animal tissue is composed of cells
  • cells are the basic unit of all life
  • cells on develop from existing cells
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3
Q

Why is light microscopy important ?

A
  • it is easily available
  • relatively cheap
  • it can be used out in the field and it can be used to observe living organisms as well as dead ones
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4
Q

How does a light Microscope work ?

A
  • it has two lenses - the objective lense ( which is near the specimen ) and an eyepiece lens ( which is where the specimen is viewed )
  • the objective lens produces a magnified image which is further magnified by the eyepiece lense
  • illumination is caused from a light beneath
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5
Q

How is the beam focused with a light mirpcroscope?

A
  • With the eyepiece and objective lense
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6
Q

How is the beam focused with a TEM / SEM microscope ?

A
  • through the use of an electromagnetic lens which focuses electrons into a very fume beam
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7
Q

What is the maximum effective magnification of a light microscope, TEM and SEM?

A

Light - x2000
TEM/SEM - 1 million

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8
Q

What’s the maximum resolution of a light microscope, TEM and SEM ?

A

Light - 200nm
TEM - less than 1nm
SEM - 1-20nm

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9
Q

What microscopes can a live specimen be used?

A

Light only
NOT TEM/SEM ( must be dehydrated and in a vacuum )

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10
Q

What methods are used when preparing a microscope slide?

A
  • dry mount
  • wet mount
  • squash slides
  • smear slides
  • staining
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11
Q

Explain dry mount in the preparation stage of microscopy?

A
  • the specimen is placed on the centre of the slide and the cover slip is placed on top
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12
Q

Explain wet mount in the preparation stage of microscopy

A
  • specimen are suspended in a liquid ( eg. water ) and then a cover slip is placed at an angle
  • this allows for aquatic samples to be viewed
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13
Q

Explain squashing slide stage of microscopy

A
  • a wet mount is first prepared
  • then a lens tissue is Bentley pressed on the cover slip
  • this prevents damage to the cover slip
  • eg. Root tip squashes to look at cell division
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14
Q

Explain smear sliding stages of microscopy

A
  • the edge of the slide is used to smear the sample which creates a thin coating on another slide
  • the cover slip is then placed on top
  • good way to view blood cells
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15
Q

Explain the use of staining in light microscopy ( include differential staining )

A
  • Some cell components and cells are difficult to see unless they are stained a more obvious colour.
  • Differential staining is a technique which involves many chemical stains being used to stain different parts of a cell in different colours.
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16
Q

what is magnification ( formula ) ?

A

magnification = size of image / size of real object

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17
Q

What is magnification ( definition ) ?

A
  • how many times larger the image is than the actual size of the object
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18
Q

What is resolution ( definition ) ?

A
  • The ability of a magnified image to determine between two separate points
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19
Q

How do you measure the size of a sample under a microscope?

A
  • you use an eyepiece graticule
  • it’s a large disc marked with a fine scale of 1 -100
  • ( no units )
20
Q

What’s the purpose of a stage micrometer?

A
  • it’s a microscope slide with a very accurate scale in micrometers
21
Q

Steps to calibrating are :

A
  1. Put the stage micrometer in place and the eyepiece graticule in the eyepiece
  2. Get the scale on the micrometer to focus
  3. Align the micrometer with the scale in the eyepiece
  4. The take readings from both scales
  5. Use them to calculate the measurements of the specimen
22
Q

What is laser scanning microscopy ?

A
23
Q

What is a cell ? And what are they types?

A
  • it’s the basic unit of all living cells
  • either prokaryotic or eukaryotic
24
Q

What are prokaryotic cells?

A
  • these are singled celled organisms
  • they have a simple structure of just a single undivided internal area called cytoplasm
25
Q

What are eukaryotic cells?

A
  • they make up multicellular organisms like animals, plants and fungi
  • they have a more complicated internal structure - containing membrane bound cellular components
26
Q

Nucleus : function

A
  • directs cells activity
  • contains instructions - found on DNA
  • largest organelle
27
Q

Nucleolus: function

A
  • area within the nucleus
  • produces ribosomes
  • composed of proteins and RNA
28
Q

Nuclear envelope : function

A
  • separates nucleus and cytoplasm
  • controls movement in or out
29
Q

Rough ER : function

A
  • a series of folded molecules that move material around the cell
  • have ribosomes attached
  • responsible for synthesis and transport of proteins
30
Q

Smooth ER : function

A
  • responsible for lipid and carbohydrate synthesis and storage
31
Q

Golgi apparatus : function

A
  • it’s role is to modify proteins and packaging them into vesicles
  • either into secretory vesicles ( leave the cell )
  • or into lysosomes ( stay in the cell )
32
Q

Vesicles : function

A
  • are scams that have storage and transport roles
  • single membrane with fluid inside
33
Q

Lysosomes : function

A

-special forms of vesicles that contain hydrolytic enzymes
- these break down waste materials in cells
- plays an important role in the immune system

34
Q

Ribosomes : function

A
  • they produce proteins
  • float freely or attach to ER
  • made in nucleus
35
Q

Mitochondria : function

A
  • organelles that release energy
  • this is released by breaking down food into C02
36
Q

Chloroplasts : function

A
  • green organelle that’s makes food
  • contain CHLOROPHYLL which has a green pigment and captures sun energy which is used to make food
37
Q

Plasma membrane : function

A
  • it’s a protective layer
  • allows food / water / 02 in
  • allows cell waste and C02 out
38
Q

centrioles : function

A
  • component of the cytoskeleton
  • two form centrosome
  • which are involved in the assembly and organisation of spindle fibres during cell division
39
Q

Flagella : function

A
  • used to enable cells mobility
  • in some cells they are a sensory organelle that detect chemical changes in a cells organism
40
Q

Cilla : function

A
  • either mobile or stationary
  • they beat in a rhythmic manner which creates a current and causes fluids or substances to move
  • eg in lungs ( trachea )
41
Q

What are the steps of protein production?

A

1 - MRNA is made in the nucleus ( transcription )
2 - MRNA leaves the nucleus via a nuclear pore
3 - it then travels to the rough ER
- translation occurs - MRNA made into polypeptide
4 - polypeptide moves through the rough ER and is folded and given 3D structure
5 - the end of the rough ER - folded protein is now in a vesicles - to prevent cytoplasm enzymes breaking it down
6 - then travels down to Golgi - the membrane fuses with it
7 - modification in the Golgi ( eg. If a carbohydrate is added becomes a glycoprotein )
8 A - if the protein will remain in the cell it will bud of the Golgi ( eg . RNA polymerase)
8 B - protein buds of the Golgi and leaves the cell in exoytosis

42
Q

What is the cytoskeleton ? What is it made of .

A
  • scaffolding like in the cytoplasm
  • it helps maintain the shape
  • made of microfilement, intermediate filaments and microtubles
43
Q

What are micro filaments?

A
  • 7nm in diameter
  • rod like and made of protein actin
  • they are polymers of actin
    PURPOSE- they give support and mechanical strength and allow cell movement
44
Q

What are intermediate filaments?

A
  • 10 nm in diameter
  • made up of a series of proteins
    PURPOSE- also provide strength and support + form spindle fibres before cell divides
45
Q

What are microtubles?

A
  • they are straight cylindrical tubes made of protiens subunits
  • 18 - 30 nm
    PURPOSE- anchor the nucleus within the cytoplasm + extend some cell tissue and allowing cells to adhere to a basement membrane

Biology (5 decks)

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