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Biology > Cell structure > Flashcards

Cell structure Flashcards

1
Q

Describe the function of the plasma membrane/ bilayer

A
  • controls passage of molecules in and out of the cell
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2
Q

Describe the function of the nucleus

A
  • contains DNA which codes for proteins
  • site of DNA replication and production of mRNA (in transcription) and tRNA
  • nucleolus makes ribosomes
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3
Q

Describe the function of the mitochondria

A
  • carry out aerobic respiration producing ATP
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4
Q

Describe the function of the lysosomes

A

vesicles containing lysozymes which cause hydrolysis

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5
Q

Describe the function of the ribosomes

A
  • protein synthesis
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6
Q

Describe the function of the rough endoplasmic reticulum

A
  • has ribosomes which synthesise proteins
  • it transports proteins through the cell
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7
Q

Describe the function of the smooth endoplasmic reticulum

A
  • synthesises and transports lipids
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8
Q

Describe the function of the golgi apparatus

A
  • processes, modifies and packages proteins into vesicles for secretion
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9
Q

Describe the function of the chloroplasts

A
  • site of photosynthesis. They contain their own DNA and ribosomes for chloroplasts to make their own enzymes for photosynthesis
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10
Q

Describe the function of the cellulose cell wall

A
  • gives cells and organisms support , prevents cell from bursting
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11
Q

Describe the function of the Vacuole

A
  • helps to maintain pressure inside the cell and keep the cell rigid
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12
Q

Define the terms eukaryotic and prokaryotic

A

Eukaryotic= cell contains a membrane bound nucleus
Prokaryotic= cell doesn’t have a nucleus but DNA in the cytoplasm

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13
Q

Compare and contrast the structure of a plant cell and fungal cell

A

Comparison=
- Both cells contains a nucleus
- Both have a cell- surface membrane
- Both have a golgi apparatus

Contrast=
- Fungal cell walls are made of chitin whereas plant cell walls are made of cellulose
- Fungal cells don’t have chloroplasts but plant cells do

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14
Q

Compare and contrast the structure of a plant and algal cell

A

Comparison=
- Both cells contain a vacuole
- Both cells contain a cellulose cell wall
- Both algal and plant cells have linear DNA in the nucleus

Contrast=
- Algal cells often have 1 large chloroplast whereas plant cells have lots of smaller ones

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15
Q

Compare and contrast a prokaryotic and eukaryotic cell

A

Comparison=
- Both prokaryotic and eukaryotic cells contain cell- surface membranes
- Both contain ribosome

Contrast=
- In prokaryotes, DNA is circular and not associated with histone proteins whereas in eukaryotes DNA is linear and associated with histone proteins.
- Eukaryotes have nuclei, but prokaryotes don’t
- Prokaryotic cells are much smaller than eukaryotic cells
- Prokaryotic cells have smaller 70s ribosomes whereas eukaryotic cells have larger 80s ribosomes

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16
Q

Compare and contrast an optical and electron microscope

A

Contrast=
- LM use light to gain an image whereas EM use a beam of electrons
- LM has a lower resolution than an EM
- EM produce a black and white image whereas LM produce a colour image.
- LM specimen can be alive but in EM it has to be dead
- EM needs a more time consuming staining process

Comparison=
- Both can be used to view large organelles in a cell
- Both can be used to observe dead specimens
- The samples have to be thin for both microscopes

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17
Q

Name some eukaryotic and prokaryotic organisms

A

P= bacteria
E= animal, plant, algal, fungal

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18
Q

Name the organelles in a bacterial cell

A

Cell-surface membrane
Murein cell wall
Capsule
Flagellum
DNA
cytoplasm
Plasmid

19
Q

Name the organelles of a virus particle

A

Capsid (protein coat)
Core genetic information (DNA or RNA)
Attachment proteins

20
Q

Explain how optical microscopes work and their limitations

A

Specimens are illuminated with light which is focused using glass lenses and viewed using the eye. Specimens can be living or dead but often need to be stained to make certain organelles visible

Limitations=
- resolution is lower, can only see large organelles, limited by the long wavelength of light

21
Q

Explain how electron microscpes work and their limitations

A

Electrons microscopes use a beam of electrons to image the specimens. It can see small organelles and the internal structure of organelles. They have a higher resolution as wavelength of electrons is shorter.

Limitations=
- Specimens must be viewed in a vacuum so must be dead
- require a more time- consuming staining process
- must be very thin can be difficult

22
Q

State the equation for magnification

A

magnification= image size/ actual size

23
Q

State some examples of artifacts

A

dust, fingerprints, air bubbles

24
Q

Define resolution

A

the ability to distinguish between 2 objects which are close together as 2 separate objects

25
Q

Describe the function of attachment proteins in virus replication

A

These are used to attach to host cells so the virus can enter the cell and use the cell to replicate

26
Q

Describe the procedure for separating cell organelles using cell fractionation and ultracentrifugation

A
  1. Tissues homogenised to break open cells and release organelles
  2. Tissues placed in an ice cold, isotonic, buffered solution
  3. Mixture is then filtered to remove any unbroken cells and cell debris
  4. The solution is then centrifuged at a low speed to pellet the most dense organelles (nucleus)
  5. The supernatant is removed and placed in a new tube and centrifuged at a faster speed to pellet less dense organelles. This is differential centrifugation.

1st pellet= nucleus
2nd pellet= chloroplasts or mitochondria
3rd pellet= other organelles
4th pellet= ribosomes

27
Q

Explain why an ice cold, isotonic and buffered solution is used

A

Ice cold= reduces enzyme activity to prevent damage to organelles
Isotonic= prevents osmosis so organelles don’t burst or shrink
Buffered= prevents changes in pH so proteins in organelles don’t denature

28
Q

Compare and contrast a scanning and transmission microscope

A

Contrast=
- TEM has a higher resolution than SEM
- A SEM produces a 3D image whereas TEM can only produce a 2D image
- TEM can see the internal structures of organelles (electrons transmitted through specimen) whereas SEM can only see the surface of the specimen (deflected off the specimen)

Comparison=
- Both use a beam of electrons to gain an image
- The images produced in SEMs and TEMs are black and white
- In both microscopes the specimens have to be dead as their placed in a vacuum

29
Q

Describe the structure of the ribosome

A
  • made of proteins and rRNA
  • small subunit and large subunit
30
Q

Whats the strucuture of the nucelus?

A
  • double membrane with pores
  • surrounded by nuclear envelope
  • contain a nucleolus- makes ribosomes
  • contains chromatin coiled into chromosomes
31
Q

What’s the structure of the rough endoplasmic reticulum?

A

made of flattened membrane sacs called cristae

32
Q

Describe the structure of the smooth endoplasmic reticulum?

A

made of flattened membrane sacs called cristae

33
Q

What’s the membrane surrounding the vacuole called?

A

Toroplast

34
Q

Describe the structure of the mitochondria

A
  • has a double membrane
  • inner membranes folded to form cristae (s)
  • Matrix (inside the inner membrane) contains DNA and ribosome used to make enzymes for aerobic respiration
35
Q

Name the structures found in the chloroplasts

A
  • granum
  • ribosomes
  • lamella
  • stroma
  • starch grains
36
Q

What is the function of the granum in the chloroplasts?

A

stack of thylakoid membranes which increases surface area for absorption of light

37
Q

What is the function of the thylakoid membrane in the chloroplasts?

A

in the granum and lamella
increases surface area for absorption of light

38
Q

What is the function of the stroma in the chloroplasts?

A

fluid filled matrix contains enzymes for some of the photosynthetic reactions

39
Q

What is the function of the starch grain in the chloroplasts?

A

storage molecule

40
Q

Describe how you could prepare a piece of plant tissue to view using an optical microscope (4)

A
  1. Add a drop of water to the slide
  2. Prepare a thin section of tissue and place on slide
  3. Stain the cells (iodine in potassium iodide solution)
  4. Lower cover slip onto cells using mounted needle
41
Q

Describe how the student could use an eyepiece graticule to determine the mean diameter of stomata (3)

A
  1. Calibrate eyepiece graticule against stage micrometre
  2. Measure using eyepiece graticule
  3. Take a large number of measurements to calculate a mean
42
Q

Describe the method scientists could use to find the mean number of capillaries per mm2 (4)

A
  1. Calibrate eyepiece graticule using stage micrometer
  2. Measure diameter of field of view and find area
  3. Count number of capillaries in large number of fields of view and calculate mean
  4. Select fields of view randomly
43
Q

Explain the role of cholesterol in the phospholipid bilayer

A

more cholesterol reduces fluidity, more rigid

44
Q

Describe the steps of organelles working together for protein synthesis, transport and secretion

A
  1. DNA in nucleus codes for protein
  2. Protein synthesis occurs at ribosomes. Mitochondria produce ATP for this process
  3. Rough endoplasmic reticulum transports protein from ribosome to golgi apparatus
  4. Golgi modifieds and packages protein into vesicles
  5. Vesicles transport protein to cell-surface membrane and fuse with the cell-surface membrane

Biology (26 decks)

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