Ultrastructure of a generalised cell Flashcards

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1
Q

What are all membranes thought to have?

A

The same structure

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2
Q

What are membranes composed of?

A

They are composed of phospholipids and proteins

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3
Q

What type of phosphate and lipid groups do phospholipids have?

A

A water-hating lipid group and a water-loving phosphate group

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4
Q

How are phospholipids arranged?

A

They are arranged into double layers (bilayers) The phosphates are on the exposed outer surfaces with the lipids in the middle

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5
Q

Name four functions of membranes

A
  1. retain the cell contents
  2. Recognise molecules that touch them
  3. Control what enters and leaves the cell
  4. Give some support to the cell
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6
Q

What is the nucleus surrounded by?

A

It is surrounded by a double membrane with numerous nuclear pores.

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7
Q

What does the double membrane with numerous nuclear pores surrounding the nucleus do?

A

They allow the controlled entry and exit of molecules into and out of the nucleus.

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8
Q

What does the nucleus contain?

A

It contains strands of deoxyribonucleic acid (DNA). and it is arranged into structures called chromosomes

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9
Q

Why is the nucleus of a stained cell darker than the other parts of the cell?

A

As the DNA in the nucleus readily absorbs many stains and becomes darkly coloured under the microscope.

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10
Q

What does every organism have a definite number of in each nucleus? Give this number for humans nuclei

A

A definite number of chromosomes. (humans have 46)

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11
Q

Where are genes located?

A

They are located randomly along chromosomes

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12
Q

Define chromatin

A

Chromatin is the name given to chromosomes when they are elongated and not dividing

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13
Q

What are genes? What do they control?

A

Genes are the structures that inform the cell how to make certain proteins.

They control features such as the number of fingers, colour of eyes and production of enzymes

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14
Q

What are genes also known as?

A

Units of inheritance

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15
Q

When cells are not dividing what do they look like?

A

They are very elongated and interwoven. In this form they are called chromatin

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16
Q

What do nuclear pores allow?

A

They allow a type of RNA called mRNA to pass in and out of the nucleus.

17
Q

What does the nucleolus make?

A

It makes ribosomes

18
Q

Where is the nucleolus located?

A

In an area in the nucleus that stains very darkly.

19
Q

What is cytoplasm?

A

It is a jelly-like substance that surrounds the nucleus. A number of organelles are suspended in it.

20
Q

What do mitochondria provide?

A

They supply energy to the cell

21
Q

What cells produce lots of energy? Give an example in both animals and plants

A

Cells with many mitochondria produce lots of energy. An example is muscle and liver in animals, meristems in plants.

22
Q

What cells produce less energy? Give an example in both animals and plants

A

Cells with few mitochondria produce less energy. An example is fat in humans, ground tissue in plants.

23
Q

Mitochondria are the sites of what?

A

The sites of respiration

24
Q

What are mitochondria surrounded by?

A

A double membrane.

25
Q

Where is energy released in mitochondria?

A

It is on the inner membrane, especially the infoldings, that energy is released.

26
Q

What affects cellular respiration in mitochondria?

A

The more infoldings that are present the greater the surface area for cellular respiration

27
Q

What does each mitochondrion contain?

A

Its own loop of DNA

28
Q

What causes the number of infoldings in mitochondria to increase?

A

Exercise

29
Q

Answer the following in terms of chloroplasts:

  1. What are they surrounded by?
  2. What do they have that contains the green pigment chlorophyll?
  3. What do they also have similar to mitochondria?
  4. What are chloroplasts?
A
  1. Double membranes.
  2. They have membrane stacks that contain chlorophyll.
  3. They have a loop of DNA.
  4. Chloroplasts are green structures in plants in which photosynthesis takes place
30
Q

Answer the following in terms of cell walls:

  1. What are they made of?
  2. Are they impermeable or permeable?
  3. What is the cell walls function?
A
  1. Cellulose (a structural polysaccharide)
  2. They are fully permeable.
  3. The function of the cell walls is to support and strengthen the cell.
31
Q

What do plants have that animals don’t?

A

Chloroplasts, cell walls, a large vacuole

32
Q

Answer the following in terms of ribosomes:

  1. What is the function of ribosomes?
  2. What are ribosomes made of?
  3. They work by combining what to form what?
A
  1. The function of ribosomes is to make proteins.
  2. They are made of RNA and protein.
  3. They work by combining a sequence of amino acids to from a protein.
33
Q

Name all the parts of an animal cell (9)

A
Cell membrane
Nucleus
Nuclear membrane 
Nucleolus 
Chromatin 
Nuclear Pore
Cytoplasm 
Ribosome
Mitochondrion
34
Q

Name all the parts of a plant cell (12)

A
Mitochondrion
Cell wall
Cell membrane 
Nucleus 
Cytoplasm 
Vacuole 
Chloroplast
Ribosomes 
Nuclear pore
Nucleolus 
Chromatin 
Nuclear membrane
35
Q

Name the differences between a plant and animal cell

A

Plant Cells:
Have a cell wall, may have chloroplasts, have a large vacuole

Animal cells:
Don’t have a cell wall or chloroplasts or a large vacuole.