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Biology > Cell structure > Flashcards

Cell structure Flashcards

1
Q

Advantages of light microscopes.

A

Cheap, easy to use, portable and able to study living organisms.

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2
Q

What is the magnification and resolution of light microscopes.

A

The magnification is up to x1500 and some types x2000. The resolution is limited as they cannot magnify higher while still giving a clear image.

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3
Q

Difference between magnification and resolution.

A

Magnification is how big an image appears to be in comparison with the original object and resolution is the ability to show fine detail clearly so that two parts of an image don’t merge.

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4
Q

How do light microscopes work?

A

Uses visible light of a wavelength between 400 and 700nm.

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5
Q

How do laser scanning microscopes work?

A

Uses laser light to scan an object and assemble the pixel information to form the image on a computer screen.

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6
Q

How do electron microscopes work.

A

Use a beam of fast-travelling electrons with a wavelength of about 0.004nm. The electrons are fired from a cathode, focused by magnets onto a screen.

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7
Q

Advantages of electron microscopes?

A

Produce highly magnified images. Much better resolution than optical microscope.

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8
Q

How do transmission electron microscopes work?

A

Specimen is dehydrated and stained. The beam of electrons which pass through are focused

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9
Q

What resolution and magnification can be achieved using a transmission electron microscope?

A

A 2D black and white image is formed. Can magnify up to x2 million times.

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10
Q

Difference between transmission electron microscope and scanning electron microscope.

A

Transmission electron microscope produces 2D images and electrons pass through the specimen whereas scanning electron microscope produces 3D images and electrons bounce off the specimens surface.

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11
Q

Magnification and resolution of scanning electron microscopes.

A

Magnification X15 to x200,000. Image is in black and white.

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12
Q

Why are specimens stained?

A

To make the specimen or part of the specimen easy to see.

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13
Q

Function of nucleus

A

Stores genetic information and provides instructions for protein synthesis

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14
Q

Function of nucleolus

A

Where ribosomes are made

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15
Q

Function of nuclear envelope

A

Separates the contents of the nucleus from the rest of the cell

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16
Q

Function of the rough endoplasmic reticulum

A

Channels for transporting substances around the cell. Gives surface area for ribosomes to assemble amino acids is into proteins

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17
Q

Function of smooth endoplasmic reticulum

A

Contains enzymes that catalyse reaction involved with liquid metabolism such a synthesis of; cholesterol and lipids.

18
Q

Function of Golgi apparatus

A

Modifies proteins and then packages into vesicles

19
Q

Function of mitochondria

A

Sites of ATP production during aerobic respiration

20
Q

Function of ribosomes

A

Bound to the exterior of the rough endoplasmic reticulum synthesise proteins.

21
Q

Function of lysosomes

A

Engulfs old cell organelles and foreign matter and separates powerful enzymes from the rest of the cell

22
Q

Function of chloroplasts

A

The site of photosynthesis where light energy is trapped by chlorophyll to make ATP

23
Q

Function of cilia

A

Cells lining your airway is to waft mucus

24
Q

Functions of centrioles

A

Involved in formation of spindles and formation of cilia

25
Q

Similarities between prokaryotic cells and eukaryotic cells

A

Both have a plasma membrane,
cytoplasm,
ribosomes- smaller in prokaryotic
and DNA

26
Q

Differences between prokaryotic and eukaryotic cells

A

Prokaryotic cells do not have a nucleus or other membrane-bound organelles.
Cell wall is made of peptidoglycan.
Has naked DNA which floats free in the cytoplasm as a loop

27
Q

Disadvantages of scanning electron microscope?

A

Specimen must be in a vacuum

28
Q

Disadvantage of electron microscopes

A

Expensive and large

Require training to use

29
Q

What can be seen with a light microscope?

A

Human ovum and cheek cells
Mitochondria, chloroplast, bacterium
Influenza virus

30
Q

What can be seen with a electron microscope but not a light microscope?

A

Ribosome, protein
Lipids
Atom

31
Q

When are laser scanning microscopes used?

A

In medical profession

32
Q

Advantages of laser scanning microscopes?

A

Have depth selectivity
High resolution and show high contrast
Can observe living specimens

33
Q

When does a specimen not need to be stained?

A

When the specimen is transparent and colourless
When a microscope uses light interference
Use a dark background
Adjust the iris on a light microscope to reduce the illumination of the specimen

34
Q

What is differential staining?

A

A stain that binds to specific cell structures to highlight structures separately.

35
Q

Examples of differential staining?

A

Acetic orcein binds to DNA and stains chromosomes dark red
Eosin stains cytoplasm
Sudan red stains lipids
Iodine stains cellulose yellow and starch blue black but will appear violet under the microscope

36
Q

How are specimens prepared?

A

Dehydrated
Embedded in wax
Thinly sliced into sections
Stained and mounted in a preserving chemical

37
Q

Describe the cytoskeleton?

A

Network of protein structure within the cytoplasm
Rod like microfilaments
Microtubules

38
Q

Function of cytoskeleton?

A

Gives support and mechanical strength
Keeps cells shape stable and allows cell movement
Forms the track for motor proteins to move organelles around the cell
Forms spindle, anchors nucleus and enables cell movement

39
Q

What extras can prokaryotic cells have?

A

Protective waxy capsule surrounding cell wall
Small loops of DNA- plasmids
Flagella- whip like projections- enable movements
Pili- hair like projections enable passage of plasmid DNA from one cell to another

40
Q

How do prokaryotic cells divide?

A

Binary fission as they do not have linear chromosomes

41
Q

What microorganisms have eukaryotic cells?

A

Yeast and amoebae

42
Q

What do viruses not have?

A

Cells

Biology (17 decks)

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