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AQA A-Level Biology - (AS) 2024/2025 > 3.2.1.1 Structure of Eukaryotic Cells > Flashcards

3.2.1.1 Structure of Eukaryotic Cells Flashcards

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1
Q

Nucleoplasm

A

Bulk of the nucleus formed from a granular jelly

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2
Q

Nucleoulus

A

Spherical region within the nucleus which manufactures RNA and assembles ribosomes

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3
Q

Nuclear envelope

A

Double stranded, it controls what goes in and out of the cell, reactions take place here and they contain ribosomes

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4
Q

Nuclear pores

A

These allow passage of large materials e.g., mRNA

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5
Q

Chromatin in the nucleus

A

Linear DNA which is histone bound, this condenses to form visible chromosomes during nuclear division

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6
Q

List the functions of the nucleus

A

Produces mRNA and RNA for protein synthesis

DNA replication

Contains genetic information for primary structure of polypeptides

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7
Q

Double membrane (mitochondrion)

A

Controls entry and exit of substances in a cell and the inner of the 2 membranes fold to form cristae

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8
Q

Cristae

A

Extensions forming folds of the inner membranes, these provide a large surface area for enzymes involved in aerobic respiration e.g., ATP synthase

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9
Q

Matrix

A

Contains: proteins, lipids mitochondrial DNA and 70S ribosomes. By contains mitochondrial DNA, it allows mitochondria to produce its own proteins for respiration independent of a nucleus

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10
Q

Rough endoplasmic reticulum

A

Found on certain parts of the outer membrane of the nucleus

Contains ribosomes

Provides a large surface area for the synthesis of proteins

Packages proteins into vesicles and transports these to the Golgi apparatus ready for modification

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11
Q

Smooth endoplasmic reticulum

A

No ribsomes

Tube like appearance

Stores, transports and synthesis carbohydrates and lipids

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12
Q

State the definition of a eukaryotic cell (1)

A

A cell that contains a nucleus AND a membrane-bound organelles

Accept membrane bound organelles AND nucleus

Ignore any reference to prokaryotic cells

Ignore any reference to examples of organelles

Ignore any reference to diagrams

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13
Q

Golgi apparatus

A
  1. Lipids and proteins formed in the RER and SER are passed through the GA in a strict sequence
  2. These are then modified by adding carbohydrates and lipids to them forming glycoproteins and glycolipids
  3. These modified proteins are then packaged into vesicles which are regularly ‘pinched off’ from the Golgi cistarne
  4. These vesicles then fuse or move towards the cell surface membrane where they release there contents during exocytosis
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14
Q

Ribosomes

A

Formed of ribosomal RNA and protein subunits needed to synthesise proteins. They may be found in the cytoplasm or attached to the membrane of the RER. There are 2 types:
1. 70S which are smaller and found in prokaryotic cells
2. 80S which are larger and found in eukaryotic cells

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15
Q

Cell surface membrane

A
  • Controls passage of molecules in and out of the cell
  • Made up of: carbohydrates, phospholipids and specific transport proteins arranged in ‘fluid mosaic model’
  • All cell surface membranes have the same basic structure, however, the proportion of molecules varies depending on the function of the cell.
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16
Q

Draw and label a nucleus

A

See notes

17
Q

Draw and label a mitochondrion

A

See notes

18
Q

Draw and label a lysosome

A

See notes

19
Q

Lysosomes are produced by which organelle?

A

Golgi apparatus

20
Q

An important structure of a eukaryotic cell is lysosomes.

Describe the general behaviour and structure of lysosomes

A
  • Contains and releases hydrolytic enzymes
  • Contains and releases lyzozomes (enzyme)
  • It is single membrane and in a spherical shape
  • They isolate the hydrolytic enzymes before release so that there is no unwanted breakdown of the cells ultrastructure
21
Q

List the functions of lysosomes

A
  • Fuse with foreign materials ingested by phagocytic cells and release hydrolytic enzymes
  • Release enzymes to the outside of the cell in exocytosis to break down molecules
  • Breakdown damaged and worn out organelles so the useful molecules they’re built from can be restored
  • Completely break down dead cells (autolysis)
22
Q

Describe the role of organelles in eukaryotic cells for the production, transport and release of proteins (6)

A
  1. DNA in the nucleus codes for proteins
  2. Ribosomes/RER produce proteins
    Allow synthesise proteins
  3. Mitochondria produce ATP (for protein synthesis)
    Reject any reference to energy
  4. Golgi apparatus modify and package proteins
  5. Vesicles transport proteins
  6. Vesicles fuse with cell (surface) membrane during exocytosis
23
Q

What do plant cells contain that animal cells do not?

A
  • Large central vacuole containing cell sap
  • Chloroplasts
  • Cell wall
24
Q

What is the main storage difference between animal and plant cells?

A
  • Animal cells store carbohydrates as glycogen
  • Plant cells store carbohydrates as starch
25
Q

Draw and label the structure of a chloroplast

A

See notes

26
Q

Draw out and label the structure of a chloroplast

A

Include:
- Inner membrane and outer membrane
- Granum
- Thylakoid
- Starch grain
- 70S ribosomes
- DNA
- Stoma

27
Q

Describe the structure of a chloroplast

A
  1. Site of photosynthesis
  2. The chloroplast envelope is a double membrane, it is highly selective and controls what goes in and out.
  3. Inside, is the grana, these are stacks of (up to 100) disc shaped thylakoid which contain membranes
  4. Thylakoid membranes contain the photosynthetic pigment chlorophyl, the first stage of photosynthesis takes place here
  5. The stroma is a fluid filled matrix, which contains photosynthetic enzymes and starch grains. The second stage of photosynthesis takes place here
28
Q

Outline the functions of a chloroplast

A
  • The thylakoid membrane has a large surface area so that lots of (the photosynthetic pigment) chlorophyll can be stored
  • Chloroplasts contain their own circular DNA and ribosomes so that they can form there own proteins for photosynthesis
29
Q

Draw and label the structure of a cellulose cell wall

A

See notes

30
Q

Describe the structure and functions of a cellulose cell wall

A
  • Straight chains of beta glucose are held together by many (weak) hydrogen bonds forming microfibril
  • These provide strength, stability and rigidity
  • They prevent the cell from bursting due to pressure of water entry by osmosis
31
Q

Draw and label the structure of a vacuole

A

See notes

32
Q

Outline the structure and functions of a vacuole

A
  • Fluid containing sack bound by a single membrane called a tonoplast
  • Contains: mineral salts, waste, amino acids, sugars, and sometimes pigment
  • It provides support - keeps the cell turgid
  • Pigment attracts pollinating insects
33
Q

State the differences a prokaryotic cell has compared to a eukaryotic cell (6)

A
  • DNA is circular, not histone bound and contains no introns
  • No true nucleus, DNA is found free in the cytoplasm
  • Contains smaller 70S ribosomes
  • Cell wall is made of glycoprotein meurin (plant cell walls are made of cellulose)
  • No membrane-bound organelles
  • Contains: capsule, one or more plasmids and one or more flagella
34
Q

Describe the structure of a virus

A
  • Acellular, non-living
  • Small, requires living cell to replicate
  • Contains single/double-stranded DNA/RNA
  • Genome is surrounded by protein coat called capsid
  • Envolope contains attachment proteisn to bind to host cell
  • Has enzymes to replicate genetic information and replicate in host cells
  • No organelles - can’t synthesise proteins or DNA
  • Some viruses are called retroviruses e.g., HIV. These contain the enzyme reverse transcriptase allowing them to produce a copy of DNA from viral RNA
35
Q

One key function of lysosomes

A
  • Fuse with vesicles
  • Release hydrolytic enzymes
  • Break down

AQA A-Level Biology - (AS) 2024/2025 (7 decks)

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