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Biology - Unit 2 Cells > Cell structure > Flashcards

Cell structure Flashcards

1
Q

What is a eukaryote?

A

An organism of 1 or more cells with DNA in a membrane bound nucleus
- Animals, Plants, Fungi

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2
Q

Name the structures in an animal cell

A

Nucleus
Vacuole
Ribosomes
Mitochondria
Cytoplasm
Cell surface membrane
Glycogen Granule
Golgi Body
Golgi Vesicle
Smooth Endoplasmic reticulum
Rough Endoplasmic Reticulum

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3
Q

Name the structures in a plant cell

A

Cytoplasm
Cell wall
Cell membrane
Vacuole
Mitochondria
Nucleus
Nucleolus
Chloroplast
RER
Golgi body
Starch grains

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4
Q

Storage in Animal cells

A

Glycogen Granule

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5
Q

Storage in Plant cells

A

Starch grains

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6
Q

What is the structure of ribosomes?

A
  • 2 Sub units
  • Each ribosome made up of ribosomal RNA (rRNA) and proteins
  • Ribosomes are either free in the cytoplasm or attached to the RER
  • 80S ribosomes in eukaryotic cells
  • 70S ribosomes in prokaryotes, mitochondria and chloroplasts
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7
Q

What is the function of ribosomes?

A

Site of protein synthesis

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8
Q

Structure of rough endoplasmic reticulum?

A

-Connected to nuclear membrane
-Flattened sacs of membrane (cisternae) filled with fluid
- Studded with ribosomes (‘rough’ with ribosomes)

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9
Q

What is the function of the RER?

A

It transports polypeptides (simple proteins) which are made at the ribosomes

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10
Q

Structure of the smooth endoplasmic reticulum

A

Same as RER
BUT
no ribosomes in the membrane

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11
Q

What is the function of the SER

A

Synthesises and transport lipids

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12
Q

What are cisternae?

A

Flattened membrane bound sacs
in SER AND RER
The membranes allow the contents to be kept separate from the cytoplasm of the cell

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13
Q

What is the structure of the golgi body?

A
  • Cisternae - flattened membrane sacs filled with fluid
    Usually has vesicles budding off - membrane bound ‘packages’ of molecules
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14
Q

What is the function of the golgi body?

A

Adds carbohydrates to proteins received from RER to form glycoproteins
- Modifies simple polypeptides into functional proteins and packages them into golgi vesicles for transportation
- Processes and packages lipids
- Makes lysosomes

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15
Q

What are the golgi vesicles ?

A

Vesicles move to and fuse with the golgi body
They contain the proteins produced in the RER
They are packaged and processed in the golgi body
They bud off and are delivered to where they’re needed

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16
Q

What is the structure of lysosomes?

A

Specialised vesicle (single men range package)
Contains enzymes called lysozymes
Tiny bags of digestive enzyme

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17
Q

What is the function of lysosomes?

A

Digest material from phagocytosis
Engulf and digest non-functioning organelle
Release enzymes out of the cells

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18
Q

what are hydrolytic enzymes?

A

Enzymes that break biological molecules down

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19
Q

What is the structure of the vacuole?

A

In plants - Large, permanent and bound by a single membrane called the tonoplast

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20
Q

What is the function of the vacuole?

A

In plants — Storage site for molecules such as water and glucose
Helps keep a pant turgid

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21
Q

What are the structures in the nucleus?

A

RER
Ribosomes - on the RER
Nucleoplasm - Like cytoplasm
Nucleolus - Circle
Nuclear envelope - squares around the big circle
Nuclear pore - gaps between the nuclear envelope
Chromatin - unwound dna

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22
Q

What is the function of the Nucleus

A

-Contains DNA which codes for the sequence of amino acids in proteins
-DNA undergoes replication in the nucleus
- DNA is the template for mRNA production in protein synthesis

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23
Q

What is the function of the nucleolus?

A

Makes rRNA - which is sort of ribosomes

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24
Q

What is the structure of the Nuclear envelope ?

A

Double membrane
envelope contains holes called nuclear pores

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25
Q

What is the function of the nuclear envelope

A

Allows passage of molecules into/out of nucleus

26
Q

What is the function of the nucleoplasm?

A

Contains DNA in the form of protein bound linear DNA as chromosomes

27
Q

What is the function of chromatin?

A

Made up of DNA and proteins
Provides the instructions for the cell

28
Q

What are histones?

A

Chromosomes have histones which are DNA binding proteins
Strands of DNA wrap around histones to form a structure called a nucleosome
A chain of nucleosides is called chromatin

29
Q

What is the structure of mitochondria?

A

Double membrane
Folds on the inner membrane called cristae which increase the surface area for respiration
Contains circular DNA and ribosomes
Cylindrical shape increases SA:V ratio for efficient diffusion of oxygen in

30
Q

What is the function of mitochondria

A

Site of ATP production by aerobic respiration
The matrix formed by the cristae contains enzymes needed for aerobic respiration producing ATP

31
Q

What is the structure of chloroplasts?

A

Double membrane
Contains circular DNA and ribosomes
Thylakoids - Flattened membrane sacs containing chlorophyll to absorb light
Granum - **Stacks of thylakoids which increase the SA for the chlorophyll molecules which absorb light for photosynthesis
Stroma - **Fluid that the thylakoids are suspended in containing enzymes sugars and starch granules

32
Q

What is the structure of the cell membrane ?

A

A structure made mainly for phospholipid and proteins
On the outside of animals cells and below the cell wall of plant cells

33
Q

What is the function of the cell membrane ?

A

Regulates the movement of substances into and out of the cell

34
Q

What is the structure of the cell wall

A

Rigid structure that surrounds cells in plant, algae and fungi
Plant cell wall - Made of cellulose microfibrils )which priced strength) embedded in a matrix
Algae cell wall - Cellulose/Glycoproteins
Fungi cell wall - chitin - a nitrogen containing polysaccharide

35
Q

What is the function of the cell wall?

A

Supports the cell and prevents them from changing shape or lysing

36
Q

Cell organisation

A

Cell -> Tissue -> Organ -> Organ system -> Organism

37
Q

What is a prokaryote ?

A

An organism whose DNA is ‘free’ in the cytoplasm
Organism with simple structure, containing few organelles
- None of the organelles have a membrane

38
Q

What are the structure found in prokaryotic cells?

A

Genetic/Nuclear material
Cytoplasm
Ribosomes
Flagellum
Cell wall
Capsule
Cell surface membrane
Plamsid

39
Q

What is genetic/nuclear material

A

Large circle of DNA

40
Q

What is the cytoplasm

A

Jelly like containing enzymes and other soluble materials

41
Q

What are the ribosomes

A

70S
Smaller than in eukaryotic cells

42
Q

What is the cell wall in prokaryotic

A

most have murein cell walls
made of polypeptide and polysaccharides

43
Q

What is the cell surface membrane

A

Selectively permeable, substances enter/leave

44
Q

What is the flagellum?

A

Used for locomotion
Allows cell movement

45
Q

What is the capsule ?

A

layer of slime
stops the cell drying out
protects the cell

46
Q

What are plasmids?

A

small circular pieces of dna

47
Q

What are Viruses ?

A
  • ‘Particles’ - a-cellular (not made of cells) and non living
48
Q

What is the structure of a virus ?

A

-Contains generic material (nucleic acid - DNA/RNA)
- A capsid - consisting of protein
- Attachment proteins - often glycoproteins - attach to specific host cells

49
Q

What is differential centrifugation ?

A

Used to separate/isolate different organelles in a cell
Separates different structures of different density
Cell fractionation is the process used to separate cellular components while preserving individual functions of each components

50
Q

Steps of cell fractionation

A

1) Homogenisation
2) Filtration
3) Ultracentrifugation

51
Q

What is homogenisation?

A

Cells are first broken open in a blender called a homogeniser
- This releases the organelles

52
Q

Homogenisation conditions

A

Ice cold
Buffer
Isotonic

53
Q

Why ice cold

A
  • Low kinetic energy minimises enzyme reactions
  • Prevents autolysis (self digestion) of organelles by hydrolytic enzymes released from lysosomes
54
Q

Why a buffer?

A

Maintains the pH which prevents denaturation of proteins

55
Q

Why isotonic

A

Prevents movement of water in/out of organelles by osmosis
This prevents them from bursting or shrivelling

56
Q

Step 2 - Filtration

A

The homogenised cells are passed through a gauze
This separates the debris from the organelles

57
Q

Step 3 Ultracentrifugation

A

The homogenate (homogenised cells) is poured into a tube placed in a centrifuge
The centrifuge spins the tube to separate organelles based on density

58
Q

Ultracentrifugation procedure

A
  • Homogenate is spun in a centrifuge
  • Most dense organelle form a pellet at the bottom of the tube
  • Less dense ones remain in the supernatant (liquid)
  • Spin faster for longer to get the second most dense organelle
  • Repeat
59
Q

Organelle isolation order

A

Naughty - Nuclei
Clever - Chloroplast (if in plant cell)
Monkeys - Mitochondria
Like - Lysosomes
Eating - Endoplasmic reticulum
Raspberries - Ribosomes

60
Q

What are isolated organelles used for ?

A

To investigate the function of individual cell component
eg respiration in mitochondria

61
Q

Which organelles have a double membrane

A

Nucleus
Mitochondria
Chloroplasts

Biology - Unit 2 Cells (4 decks)

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