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Biology > 1. Cells > Flashcards

1. Cells Flashcards

0
Q

Describe the structure of a Nucleus

A

Largest organelle. Contains Chromatin. Surrounded by a nuclear envelope. Contains nuclear pores. Contains a nucleolus.

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1
Q

Describe the structure of Centrioles

A

Small tubes of protein fibres (micro tubules).

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2
Q

What is the function of a Nucleus?

A

Contains genetic material - the instructions for making proteins.

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3
Q

Describe the structure of Rough Endoplasmic Reticulum

A

A series of membrane-bound sacs called Cisternae. Continuous with the outer nuclear membrane. Encrusted with Ribosomes.

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4
Q

What is the function of Rough Endoplasmic Reticulum?

A

Process and Package Proteins.

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5
Q

What is the function of Centrioles?

A
  • Involved in the organisation of the microtubules that make up the cytoskeleton
  • Form spindle used to move chromosomes in nuclear division
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6
Q

What is the function of Smooth Endoplasmic Reticulum?

A

Process and Package Lipids

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7
Q

Describe the structure of Golgi Apparatus

A

A stack of membrane-bound, flattened sacs.

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8
Q

What is the function of a Golgi Apparatus?

A

Modifies Proteins from Rough ER, eg adding sugar molecules.

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9
Q

Describe the structure of a Mitochondrion

A

Spherical or Sausage shaped. Two membranes seperated by a fluid filled space. Inner membrane folded to form Cristae. The central part is called the matrix.

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10
Q

Describe the structure of a Lysosome

A

Spherical sacs surround by a single membrane.

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11
Q

What is the function of a Lysosome?

A

Contains Digestive Enzymes.

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12
Q

Describe the structure of a Ribosome

A

Tiny organelles. Some in cytoplasm and some bound to RER. Consists of two subunits.

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13
Q

Describe the structure of a Plasma membrane

A

Found on the surface of animal cells and under cell walls of plant cells. Made of mainly lipids and protein.

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14
Q

What is the function of a Plasma membrane?

A

Regulates movement of substances into and out of the cell. Receptor molecules on it allow it to respond to chemicals like hormones.

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15
Q

What is the function of Cell walls?

A

Supports plant cells.

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16
Q

Describe the structure of a Vesicle

A

A small fluid filled sac in the cytoplasm, surrounded by a membrane.

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17
Q

What is the function of a vesicle?

A

Transports substances in/out of the cell and between organelles.

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18
Q

What is the function of a Ribosome?

A

The site of Protein Synthesis. Where mRNA is used to assemble proteins from amino acids.

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19
Q

What is the function of a Chloroplast?

A

Site of Photosynthesis.

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20
Q

Describe the structure of Cilia

A

Small, hair like structures found on the surface of animal cells. Their cross section contains a ring of nine pairs of micro tubules with a single pair in the centre.

21
Q

Describe the structure of a Cell wall

A

A rigid structure that surrounds plant cells. Made mainly of cellulose.

22
Q

What is the function of Cilia?

A

The micro tubules allow the cilia to move, allowing substances to be moved along the cell surface.

23
Q

Describe the structure of a Flagellum

A

They stick out of the cell surface, and are surrounded by plasma membrane.

24
Q

What is the function of Flagella?

A

The micro tubules contract to make the flagellum move, acting as an outboard motor, propelling the cell forward.

25
Q

What is the maximum resolution of a TEM?

A

0.0001um

26
Q

What organelles do Plant cells have that Animal cells don’t?

A
  • A Cell wall with Plasmodesmata
  • A Vacuole
  • Chloroplasts
27
Q

Outline what occurs in Protein production

A
  1. Ribosomes make Proteins
    (Ribosomes on rough ER make extrinsic proteins, and free ribosomes make intrinsic proteins).
  2. Proteins produced at the rough ER are folded and processed (eg. a sugar chain added).
  3. A vesicle uses ATP to transport the protein along the cytoskeleton to the Golgi Apparatus.
  4. Here, the protein undergoes further processing.
  5. A vesicle used ATP to transport the protein to the cell surface.
  6. The vesicle membrane fuses to the plasma membrane and the Protein is secreted.
28
Q

Describe the structure of a Chloroplast

A

A small, flattened structure, surrounded by a double membrane. Thylakoid membranes are stacked up inside to form Grana. Grana are joined together by lamellae - thin flat pieces of thylakoid membrane.

29
Q

What is a Cytoskeleton?

A

A network of Protein Threads. Arranged as microfilaments (Small solid strands) and microtubules (Tiny protein cylinders).

30
Q

Describe the four main functions of the Cytoskeleton

A
  1. Supports cell organelles, keeping them in position.
  2. Helps strengthen cell; maintain its shape.
  3. Responsible for organelle transportation.
  4. Cause the cell to move.
31
Q

What is the function of a Mitochondrion?

A

Site of Aerobic respiration (Adenosine Triphosphate production).

32
Q

Describe the structure of Smooth Endoplasmic Reticulum

A

Consists of a series of flattened membrane-bound sacs called Cisternae.

32
Q

What size are Eukaryotic cells?

A

Around 10-100um diameter.

34
Q

What is the maximum resolution of an SEM?

A

0.005um

35
Q

What is the maximum resolution of a light microscope?

A

0.2um

36
Q

Describe differences between Eukaryotic and Prokaryotic cells

A

P- Circular DNA

E- Linear DNA

P- No Nucleus (free floating DNA)

E- Nucleus present

P- Cell wall made from polysaccharide, Peptidoglycan

E- No cell wall (animal), Cellulose cell wall (plant) and Chitin cell wall (fungi)

P- No membrane bound organelles (eg. mitochondria)

E- Many membrane bound organelles

P- Small ribosomes (Under 20nm)

E- Larger ribosomes (Over 20nm)

38
Q

How does a TEM microscope work?

A

Transmission Electron Microscopes use electromagnets to focus a beam of electrons, which is then transmitted through the specimen.

More dense parts of the specimen absorb more electrons, which makes them look darker on the image.

Images produced are black and white.

39
Q

What size are Prokaryotic cells?

A

Less than 2um diameter. Smaller than Eukaryotic cells.

39
Q

How is magnification calculated?

A

Length of image / Length of specimen

40
Q

How is length of image calculated?

A

Magnification x Length of Specimen

41
Q

How is length of specimen calculated?

A

Length of image / magnification

42
Q

Why are samples often stained?

A

In light microscopes and TEMs, the beam of light/electrons pass through the object.
When a sample is transparent, the beam passes straight through, producing a plain white image.

43
Q

What is resolution?

A

How detailed the image is.

How well a microscope distinguishes between two points that are close together.

44
Q

How does a SEM microscope work?

A

Scanning Electron Microscopes scan a beam of electrons across the specimen.

This knocks off electrons from the specimen, which are gathered in a cathode ray tube to form an image.
Images produced can be 3D.

45
Q

What is magnification?

A

How much bigger the image is than the specimen.

45
Q

What is the maximum magnification of a Light Microscope?

A

x 1500

46
Q

What is the maximum magnification of a TEM?

A

Over x 1,000,000

48
Q

What do you stain a sample with for a Light microscope?

A

Dye. Commonly methylene blue or eosin.

The stain is taken up by some parts of the object more than others - the contrast makes the different parts show up.

49
Q

What do you stain a sample with for a TEM?

A

Samples are dipped in a solution of heavy metals (eg. Lead).
The metal ions scatter the electrons, creating contrast.
Images produced are black and white.

50
Q

What is the maximum magnification of an SEM?

A

Less than x1,000,000

Biology (14 decks)

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