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Module 2 > Cell Struture > Flashcards

Cell Struture Flashcards

1
Q

List three ways eukaryotic cells differ from prokaryotic cells.

A

membrane bound organelles
DNA is enclosed in a nucleus
Have larger ribosomes (80S) than prokaryotic cells

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2
Q

Prokaryotic cells include bacterial cells. List the differences between Prokaryotic and Eukaryotic cells.

A

No membrane bound organelles (e.g. mitochondria, endoplasmic reticulum, golgi)
No nucleus - instead they have a single circular DNA molecule that is free in the cytoplasm and is not associated with proteins
Smaller ribosomes
Has a murein cell wall, a capsule and plasmids

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3
Q

What is the structure and function of nucleus?

A

ccontaining chromosomes, consisting of protein-bound, linear DNA within the nucleoplasm. Contains one (nucleolus) or more nucleoli

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4
Q

What is the structure and function of nuclear envelope?

A

Double membrane surrounding the nucleus with nuclear pores to let molecules in and out

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5
Q

What is the structure and function of plasma membrane?

A

Description of structure: A phospholipid bilayer with hydrophllic phosphate heads facing outwards and hydrophobic fatty acid tails facing inwards.
Function: Involved in the transport of substances via diffusion or facilitated diffusion, active transport (with the aid of proteins)

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6
Q

What is the structure and function of cytoplasm?

A

Where chemical reactions take place

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7
Q

What is the structure and function of mitochondria?

A

Site of AEROBIC respiration
Produces ATP (releases energy)
Contains short, circular DNA (not associated with proteins)
Has a double membrane. The inner membrane is folded forming cristae.
Contains smaller (70S) ribosomes (thought to have evolved from prokaryotic cells.)

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8
Q

What is the structure and function of rough endoplasmic reticulum?

A

Has ribosomes on their surface which are involved in protein synthesis
Proteins are also folded up inside the RER

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9
Q

What is the structure and function of Smooth endoplasmic reticulum?

A

Synthesis and storage of molecules such as steroids and sterols

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10
Q

What is the structure and function of Golgi Apparatus and golgi vesicles?

A

Modifies proteins (e.g. by adding carbohydrate groups to form a glycoprotein or lipid groups to make a lipoprotein)
Stores proteins
Packages proteins into vesicles
Transport vesicles to cell surface

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11
Q

What is the structure and function of Lysosomes?

A

A vesicle that contains hydrolytic enzymes (lysozymes) which are used to digest molecules

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12
Q

What is the structure and function of Chloroplast?

A

Chlorophyll absorb light for photosynthesis to produce carbohydrates
Has a double membrane. Inside there are thylakoid membranes which can form a stack called a granum (pl. grana). The grana are linked by lamellae.
Contain starch grains

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13
Q

What is the structure and function of Cell Wall

A

For strength and support

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14
Q

What is the structure and function of Vacuole

A

Tonoplast – a membrane surrounding the vacuole
When the vacuole is full of fluid the cell becomes turgid.
Temporary food store containing sugars and amino acids
Contains pigments (colour petals)

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15
Q

What is the structure and function of Flagella

A

For movement

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16
Q

What is the structure and function of Plasmids

A

Circular rings of DNA
(can reproduce independently and may give resistance to harmful chemicals such as antibiotics)

17
Q

What is the structure and function of Slime layer (capsule)

A

A ‘slime’ layer on the outside of the cell, made of polysaccharides
It provides protection for the cell and might help cells stick together

18
Q

What is the structure and function of Circular DNA (DNA in a loop)

A

Genetic material in a prokaryote (not enclosed in a nucleus)

19
Q

Define magnification

A

Magnification is how much bigger the image is than the specimen

20
Q

Define resolution

A

Resolution is the minimum distance apart that the two objects can be in order for them to appear as separate items.

21
Q

Describe the procedure to prepare a slide

A

Add a drop of water to the slide
Remove a thin section of tissue and place it onto the slide (flat as possible)
Add 1 drop of iodine dissolved in potassium iodide to stain the sample (This is only correct if it is plant tissue)
Lower a coverslip on top using a mounting needle

22
Q

Explain why it was important that the sections of tissue were thin

A

A thin section allows more light through;
allows a single layer of cells to be viewed.

23
Q

Explain why you should push down hard on the cover slip, but should not push the cover slip sideways.

A

Push hard to squash the tissue to create a single layer of cells.
Do not push sideways as this will cause the cells to roll together.

24
Q

A plant cell was observed with an optical microscope. Describe how the length of the cell could be estimated.

A

Use a stage micrometer to help us calibrate the size of the eyepiece graticule.
Measure the length of the plant cell with an eyepiece graticule.

25
Q

Why are electron microscopes used to view cells?

A

They have a HIGH resolution
because electrons have a shorter wavelength than light.
This allows you to view internal structures/organelles of a cell.
(Remember using this – Light microscope = Low resolution = Longer wavelength)

26
Q

Name two structures in a eukaryotic cell that cannot be identified using an optical microscope.

A

Mitochondrion / ribosome / endoplasmic reticulum / lysosome / cell-surface membrane

27
Q

Describe the principles and the limitations of using a transmission electron microscope to investigate cell structure.

A
  1. Electrons pass through / enter (thin) specimen;
  2. Denser parts absorb more electrons;
  3. (So) denser parts appear darker;
  4. Electrons have short wavelength so give high resolution;
    Limitations:
  5. Cannot look at living material / Must be in a vacuum;
  6. Specimen must be (very) thin;
  7. Artefacts present;
  8. Complex staining method / complex / long preparation time;
  9. Image not in 3D / only 2D images produced.
28
Q

What is the advantage of TEM (transmission) compared to SEM (scanning) is

A

Higher resolution
Allows internal structures within cells to be seen

29
Q

What is the advantages of SEM (scanning) compared to TEM is

A

Thin sections do not need to be prepared
shows surface of specimen
can have 3-D images

Module 2 (6 decks)

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