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2) Cells > 3.4 Eukaryotic cell structure > Flashcards

3.4 Eukaryotic cell structure Flashcards

1
Q

what are eukaryotic cells?

A

cells which contain a distinct nucleus and membrane-bound organelles.

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2
Q

What is the role of the nucleus?

A
  • control centre of the cell through production of mRNA and tRNA, and therefore protein synthesis.
  • Retains genetic material in form of DNA and chromosomes.
  • Makes rRNA and ribosomes
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3
Q

What are the main parts of the nucleus?

A
  • nuclear envelope
  • nuclear pores
  • nucleoplasm
  • chromosomes
  • nucleolus
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4
Q

Describe the nuclear envelope.

A

A double membrane that surrounds the nucleus.

  • outer membrane is continuous with the endoplasmic reticulum and has ribosomes on the surface.
  • controls the entry and exit of materials and contains their reaction.
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5
Q

Describe the role of the nuclear pores.

A

Allow the passage of large molecules, such as mRNA out of the nucleus.

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6
Q

Describe the nucleoplasm

A

granular jelly making up most of the nucleus.

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7
Q

Describe the chromosomes.

A

protein-bound, linear DNA

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8
Q

Describe the nucleolus

A

Small spherical region in the nucleoplasm. makes rRNA and assembles ribosomes.

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9
Q

What is the role of the mitochondria?

A
  • site of the aerobic stage of respiration.
  • Responsible for the production of ATP from respiratory substrates
    Very common in metabolically active cells such as epithelial cells from the intestines which require energy for active transport.
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10
Q

What are the main feature of the mitochondria?

A
  • a double membrane
  • cristae
  • matrix
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11
Q

What is the role of the double membrane in a mitochondrion?

A
  • controls entry and exit of material

- inner membrane is folded into extensions (cristae)

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12
Q

What is the role of the cristae in a mitochondrion?

A

Extensions of the inner membrane, provide a large SA for the attachment of enzymes and proteins involved in respiration.

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13
Q

What us the role of the matrix in the mitochondria?

A
  • contains proteins, lipids, ribosomes and DNA which allows it to make its own proteins
  • enzymes are also found there.
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14
Q

What is the role of chloroplasts?

A

the harvest sunlight to carry out photosynthesis.

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15
Q

What are the main parts of a chloroplast?

A
  • the chloroplast envelope
  • the grana
  • the tylakoids
  • the stroma
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16
Q

describe the chloroplast envelope.

A
  • double plasma membrane surrounding the organelle

- highly selective of what enters and exits

17
Q

Describe the grana and the thylakoids.

A
  • the grana are stacks of discs (thylakoids)
  • the grana is where the first stage of photosynthesis happens
  • the thylakoids contain chlorophyll
18
Q

Describe the stroma.

A
  • fluid-filled matrix where the synthesis of sugars takes place.
19
Q

How are chloroplasts adapted to their function/

A
  • the granal membranes provide a large SA for the attachment of chlorophyll, electron carriers and enzymes.
  • fluid in the stroma has all the enzymes needed to make up sugars in part 2
  • chloroplasts contain DNA and ribosomes so they can manufacture proteins needed for photosynthesis.
20
Q

What is the endoplasmic reticulum?

A
  • a 3D system of sheet-like membranes which spread through the cytoplasm and is continuous with the outer nuclear membrane.
  • membranes enclose a network of flattened sacks called cisternae
  • cells which manufacture and store lots of proteins, carbohydrates and lipids have an extensive ER, EG: epithelium of intestines.
21
Q

Describe the rough endoplasmic reticulum.

A
  • has ribosomes on its surface
  • provides large SA for synthesis of proteins and glycoproteins
  • provides a pathway for transport of materials, especially proteins
22
Q

Describe the smooth endoplasmic reticulum.

A
  • no ribosomes on surface
  • synthesises and transports lipids
  • synthesises, stores and transports carbohydrates
23
Q

describe the structure of the golgi apparatus.

A
  • similar to the SER, but more compact
  • consists of a stack of membranes that make up flattened sacs (cisternae) with small, rounded hollow structures (vesicles)
24
Q

how is the golgi apparatus related to the ER

A
  • proteins and lipids produced in the ER are passed through the GA in sequence.
  • Golgi modifies proteins and adds non-protein components
  • it labels them so they can be sorted.
25
Q

What is the function of the golgi apparatus?

A
  • add carbohydrate to proteins to make glycoproteins
  • produce secretory enzymes
  • secrete carbs
  • transport, modify, store lipids
  • form lysosomes
26
Q

How are lysosomes formed?

A

when the vesicles of the golgi apparatus contain enzymes such as proteases and lipases
- they are particularly abundant in secretory cells

27
Q

What is the role of lysosomes?

A
  • hydrolyse material ingested by phagocytic cells
  • release enzymes to the outside of the cell in order to destroy material
  • digest worn out organelles so that the useful chemicals they are made of can be reused
  • completely break down cells after they have died
28
Q

What are ribosomes?

A
  • cytoplasmic granules found in all cells
  • occur in cytoplasm or RER
  • a large and small subunit which each contain rRNA and protein
  • occur in vast numbers
29
Q

What are the 2 types of ribosome?

A

80S- found in eukaryotic cells

70S- found in prokaryotic cells, slightly smaller.

30
Q

What are the features of a cell wall?

A
  • consist of lots of polysaccharides, EG:cellulose
  • thin layer (middle lamellae) which cements adjacent walls together
  • microfibrils of cellulose strengthen the cell wall
31
Q

what are the functions of the cell wall?

A
  • provide mechanical strength to prevent cell bursting under pressure from osmosis
  • give mechanical strength to the whole plant
  • to allow water to pass along it a contribute to movement of water through the plant
32
Q

what are algae cell walls made of?

A

cellulose or glycoprotein

33
Q

what are fungi cell walls made of?

A

chitin

34
Q

Describe the vacuole.

A
  • fluid-filled
  • ## bound by a single membrane- tonoplast
35
Q

What are the functions of a vacuole?

A
  • support herbaceous plants by making cells turgid
  • sugars and amino acids in cell sap act as a temporary food store
  • pigments colour petals making them attractive to pollinating insects

2) Cells (20 decks)

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