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Cell Structure Flashcards

1
Q

What’s magnification?

A

The number of times larger an image appears, compared with the size of the object. Produce linear magnifications. X100 image is 100 times wider and 100 times longer than the original object

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2
Q

What’s an organelle?

A

Small structures within cells, each of which has a specific function

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3
Q

What’s a photomicrograph?

A

Photograph of an image seen using an optical microscope

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4
Q

What’s resolution?

A

The clarity of an image. The ability of an optical instrument to see or produce an image that shows fine detail clearly

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5
Q

Why are optical microscopes still used?

A

Relatively cheap
Easy to use
Portable and able to be used in the field as well as labs
Able to be used to study while living specimens

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6
Q

What magnification do optical microscopes allow?

A

Up to x1500

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7
Q

What’s an electron micrograph?

A

Photograph of an image seen using an electron microscope

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8
Q

Why is an optical microscopes resolution low?

A

Uses visible light which is part of the electromagnetic spectrum. It has a wavelength between 400 and 700 nm therefore structures closer than 200 nm will appear as one object

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9
Q

How to set up a optical microscope?

A

Place slide with specimen on the stage and clip into place
Rotate the nosepiece so lowest power lens is over slide.
Adjust the coarse focus know while looking into the eyepiece, until you see a clear image
Whilst viewing, adjust the iris diaphragm for optimum light
Rotate the nosepiece and bring x10 objective into place over the specimen. Look down the ocular tube and use knob to focus the image

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10
Q

How to calculate magnification?

A

Total magnification= magnifying power of objective lens x magnifying power of the eyepiece lens

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11
Q

About laser scanning microscopes?

A

Use laser light to scan object point by point, assembled by computer into one image
High resolution and high contrast
Depth selectivity and can focus on structures at different depths with specimens
Can observe while living specimens
Used in medical profession and biological research

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12
Q

What’s the wavelength of electron microscopes?

A

0.004nm

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13
Q

How do electron microscopes work?

A

Electrons fired from a cathode and focused by magnets rather than glass lenses on to a screen or photographic plate

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14
Q

About the transmission electron microscope?

A

Specimen has to be chemically fixed by being dehydrated and stained
Beam of electrons pass through specimens. Some pass through and are focused onto screen
Form 2D black image
Magnification of x2000000

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15
Q

About the scanning electron microscope?

A

Electrons don’t pass through specimen.
Cause secondary electrons to bounce off the specimens surface and be focused on to a screen
3D image with magnification up to x200000
Black and white
Specimen has to be in vacuum
Coated with fine film of metal

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16
Q

Draw backs of an electron microscope?

A

Large and very expensive
Need a great deal of skill and training
Specimens have to be dead
Metallic salt stains may be potentially hazardous to the user

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17
Q

What’s the wavelength of electron microscopes?

A

0.004nm

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18
Q

How do electron microscopes work?

A

Electrons fired from a cathode and focused by magnets rather than glass lenses on to a screen or photographic plate

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19
Q

About the transmission electron microscope?

A

Specimen has to be chemically fixed by being dehydrated and stained
Beam of electrons pass through specimens. Some pass through and are focused onto screen
Form 2D black image
Magnification of x2000000

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20
Q

About the scanning electron microscope?

A

Electrons don’t pass through specimen.
Cause secondary electrons to bounce off the specimens surface and be focused on to a screen
3D image with magnification up to x200000
Black and white
Specimen has to be in vacuum
Coated with fine film of metal

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21
Q

Draw backs of an electron microscope?

A

Large and very expensive
Need a great deal of skill and training
Specimens have to be dead
Metallic salt stains may be potentially hazardous to the user

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22
Q

Examples of specimens that can be viewed by an optical microscope?

A

Living organisms such as Amoeba
Smear preparations or human blood and cheek cells
Thin sections of animals, plant and fungal tissue

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23
Q

Observing unstained specimens

A

Some organisms are colourless or transparent. Some microscopes use light interference, rather than light absorption, in order to produce a clear image without staining
Some use a dark background

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24
Q

Why stain specimens?

A

Coloured chemicals that bind to molecules on or in the specimen. Some stains bind to specific structures so they can be easily identified
This is called differential staining

Iodine stains cellulose yellow and starch granules blue/black

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25
How to make permanently fixed slides?
Dehydrating the specimens Embedding them in a wax to prevent distortion during slicing Using a special instrument to make very thin slices called sections These are stained and mounter in a special chemical to preserve them
26
What's the magnification formula?
Magnification = image/actual
27
What's an eyepiece graticule?
A measuring device. It is places in the eyepiece of a microscope and acts as a ruler when you view an object under the microscope
28
What's a stage graticule?
A precise measuring device. It is a small scale that is placed on a microscope stage and used to calibrate the value of eyepiece divisions at different magnifications.
29
Using a stage graticule to calibrate eyepiece graticule
Insert eyepiece graticule into x10 eyepiece or microscope Place stage graticule on the stage and bring it into focus using lowest power objective Align the 2 graticules Check the value of one eyepiece division at the magnification Divide the stage graticule by the amount of eyepiece units that fit into it This gives how much each division is worth
30
What is division of labour?
Every cells can carry out its many functions efficiently
31
Structure of nucleus, nuclear envelope and nucleolus
Nucleus surrounding by double membrane called nuclear envelope. There are pores in the nuclear envelope Nucleolus has no membrane. Contains RNA Chromatic(genetic material) consisting of DNA wound around histone proteins
32
Nucleus, nuclear envelope and nucleolus function
Envelope separates contents of nucleus from rest or cell. Outer and inner nuclear membrane fuse. Here some dissolved substances and rips ones can pass through Pores enable larger substances to leave Nucleolus is where ribosome r made Chromosomes contain organisms genes ``` Nucleus Control centre of cell Stores organisms genome Transmits genetic information Provides instructions for protein synthesis ```
33
Structure of rough endoplasmic reticulum
System of membranes containing fluid filled cavities that are continuous with nuclear membrane Coated within ribosomes
34
Function of rough endoplasmic reticulum
Intercellular transport system Cisternae form channels for transporting substances from one area to another Provides large surface area for ribosomes
35
Smooth endoplasmic reticulum structure
System of membranes, containing fluid filled cavities that are continuous with the nuclear membrane No ribosomes on its surface
36
Function of smooth endoplasmic reticulum
Contains enzymes that catalyse reactions involved with lipid metabolism Synthesis of cholesterol, lipids, steroid hormones Involved with absorption, synthesis and transport of lipids
37
Structure of Golgi apparatus
Consists of a stack of membrane bound flattened sacs | Vesicles bring materials to and from here
38
Function of Golgi apparatus
Proteins are modified Packaging and pinching of vesicles Then stored in cell Or exported out of the cell
39
Structure of mitochondria
Spherical rod shaped or branched 2-5 microm. Surrounded by 2 membranes with fluid filled space between them Inner membrane highly folded into cristae Inner part is a fluid filled matrix
40
Mitochondria function
Site of ATP production during aerobic respiration Self replicating Abundant in cells where much metabolic activity takes place
41
Chloroplast structure
``` 4-10microm In plants and some protoctists Double membrane Inner membrane is continuous with thylakoids which contain chlorophyll Contains loops of DNA and starch grains ```
42
Chloroplast function
Site of photosynthesis
43
Vacuole structure
Surrounded by membrane called tonoplast and contains fluid
44
Vacuole function
Plants have large permanent vacuoles Maintains cell stability Helps support the plant
45
Lysosomes structure
Small bags formed by Golgi. Surrounded by signs membrane | Contain powerful hydrolytic enzymes
46
Lysosomes function
Keep powerful hydrolytic enzymes separate from cell | Engulf old cell organelles and foreign matter, digests them and returns parts to be reused
47
Structure of cilia and undulipodia
Protrusions from the cell and surrounded by cell surface membrane Contains microtubules Formed from centrioles
48
Function of cilia and undulipodia
Epithelial cells lining has cilia to move band of mucus Act as an antenna. Acts as receptor and allows cells to detect signals Undulipodium allows spermatozoon to move
49
Ribosome structure
``` Small spherical 20nm Made of ribosomal RNA Made in nucleolus as 2 separate subunits which combine outside envelope Either free in cytoplasm or on RER ```
50
Ribosome function
Protein synthesis
51
Centriole structure
Consists of 2 bundles of microtubules at right angles to each other Microtubules made of tingling protein subunits
52
Centriole function
The spindles | Involved in the formation of undulipodia and cilia
53
Cytoskeleton structure
Network of protein structures Rod like microfilaments made of subunits of protein actin Intermediate filaments Straight cylindrical microtubules made of protein subunits called tubulin Cytoskeleton motor proteins
54
What are cytoskeleton motor proteins?
Enzymes that have a site that binds to and allows hydrolysis of ATP as their energy source
55
Cytoskeleton function
``` Give support and mechanical strength. Cell stability Movement of organelles Movement of vesicles Spindles before cell division Cilia undulipodia and centrioles Anchor the nucleus Enables cell signalling ```
56
Cellulose cell wall structure
Made of bundles of cellulose fibres
57
Cellulose cell wall function
Strong and prevents bursting Support Maintains cell shape Permeable
58
How is a protein made and secreted
Gene that has code for protein is transcribed into a length of mRNA Pass out nuclear pores to ribosome Instructions are translated into polypeptide chain Pass into cisternae of RER and pinched off Travels to Golgi with motor proteins aid Modification Pinched off again and fuses to cell wall
59
How are prokaryotic cells similar to eukaryotic
A plasma membrane Cytoplasm Ribosomes DNA and RNA
60
How are prokaryotic cells different to eukaryotic
``` Much smaller Less well developed cytoskeleton and no centrioles No nucleus No membrane bound organelles Smaller ribosomes Naked DNA Some have- Protective waxy capsule Plasmids Flagella Pili ```
61
How do prokaryotic cells divide?
Binary fission

Biology (6 decks)

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