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Biology A-Level > Cell Structure And Microscopy: Cell Ultrastructure > Flashcards

Cell Structure And Microscopy: Cell Ultrastructure Flashcards

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1
Q

What is Chromatin?

A

is the DNA (with associated histone proteins). Contains the genetic code which controls the activity of the cell.

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2
Q

Function of Cilia

A
  • Sensory function, beat creating a current to waft fluid/mucous
  • For locomotion
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3
Q

Structure of the Large Permanent Vacuole:

A
  • Single membrane bound (membrane is called a tonoplast)
  • Contains a fluid called cell sap
  • Selectively permeable barrier
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4
Q

Function of Chloroplasts:

A

For photosynthetic reactions

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5
Q

Structure of Golgi apparatus/body:

A
  • Stacks of flattened, membrane-bound sacs (cisternae).
    These are continuously formed from the ER at one end and budding off as Golgi vesicles at the other.
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6
Q

Function of Smooth Endoplasmic Reticulum:

A

Responsible for lipid, carbohydrate, and steroid synthesis and storage.

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7
Q

Function of Golgi apparatus/body

A
  • Allows internal transport
  • Recieves proteins from RER
  • Modifies and processes molecules and packages them into vesicles
  • These may be secretory vesicles or lysosomes
  • Makes lysosomes
  • Lipid synthesis
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8
Q

Function of the Rough Endoplasmic Reticulum:

A

Site of protein synthesis

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9
Q

Function of Cellulose Cell Wall:

A
  • Gives the plant mechanical strength
  • Gives the plant cell support and it’s shape
  • Contents of plant cell can ‘push’ against the cell wall. This gives the cell (and whole plant) good support.
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10
Q

Structure of lysosomes:

A

Spherical sacs surrounded by a single membrane

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11
Q

Function of Cell Surface Membrane

A
  • Regulates the movement of substances into and out of the cell
  • Contains receptor molecules which allow it to respond to chemical like hormones
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12
Q

What is the Double Nuclear Envelope?

A

A double membrane which compartmentalises the nucleus and prevents damage. Protects the DNA.

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13
Q

Structure of Mitochondria:

A
  • Surrounded by two membranes
  • The inner membrane forms finger-like structures called cristae which increases surface area.
  • The solution inside is called a matrix which contains enzymes for respiration.
  • Mitochondrial DNA - small amounts of DNA, enable mitochondrion to reproduce and create enzymes.
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14
Q

What do intermediate fibres do?

A

They give strength to cells and help maintain integrity.

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15
Q

Structure of Flagella

A
  • Similar to Cilia but longer
  • They protrude from the cell surface and are surrounded by the plasma membrane
  • Like cilia they have a 9 +2 arrangement.
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16
Q

Function of Cell Surface Membrane

A
  • Regulates the movement of substances into and out of the cell
  • Contains receptor molecules which allow it to respond to chemical like hormones
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17
Q

Structure of Centrioles:

A
  • Component of the cytoskeleton - composed of many microtubules.
  • Small hollow cylinders that occur in pairs next to the nucleus in animal cells only.
  • Each centriole contains a ring of 9 triplet microtubules.
18
Q

Function of Nucleus:

A
  • Controls all the activity of the cell
  • Where the DNA of the cell is stored, replicated and copied into RNA (transcribed)
  • The nucleus is attached to the Rough ER so the mRNA can easily get to ribosomes.
19
Q

Structure of Cell Surface Membrane:

A
  • The membrane found on the surface of animal cells and inside the cell wall of plant and prokaryotic cells.
  • A phospholipid bilayer
  • Composed of proteins and lipids
20
Q

What are microtubules?

A

Formed by the globular protein tubulin. They polymerise to form tubes that determine the shape of the cell. They also act as tracks for organelles moving around the cell.

21
Q

Function of the Ribosomes:

A

These are where proteins are made and they assemble amino acids into proteins in chains using mRNA.

22
Q

Function of Large Permanent Vacuole

A
  • Stores cell sap
  • Support herbaceous plants by making cells turgid
  • Helps maintain shape and gives support by maintaining turgor pressure
  • Sugars and amino acids act as a temporary food store
23
Q

Structure of Cellulose Cell Wall:

A
  • Made of B-cellulose microfibrils - complex carbohydrate
  • Cell wall is fully permeable to substances
  • Thin layer called the middle lamella which marks the boundary between adjacent cell walls and ‘cements’ adjacent cells together.
24
Q

Structure of Cell Surface Membrane:

A
  • The membrane found on the surface of animal cells and inside the cell wall of plant and prokaryotic cells.
  • A phospholipid bilayer
  • Composed of proteins and lipids
25
Q

Structure of Chloroplasts

A
  • Double membrane which encloses the stroma
  • Series of membrane-bound flattened sacs called thylakoids in the stroma. Thylakoids stacked together are called grana.
  • Grana are linked together by lamellae
  • The grana contain chlorophyll
26
Q

Function of Flagella:

A
  • (whip-like) enables a cells mobility
  • The microtubules contract to make the flagellum move
  • Propel cells forward e.g. sperm cells
27
Q

Structure of Cilia:

A
  • ‘Hair-like’ extensions that protrude from some animal cell types.
  • In cross section they have an outer membrane and a ring of nine pairs of protein microtubules inside with two microtubules in the middle (known as the 9 +2 arrangement)
  • Arrangement allows movement
28
Q

Function of Centrioles:

A

Makes a copy of itself during cell division and then helps to form the spindle in cell division.

29
Q

Function of lysosomes:

A
  • They contain powerful hydrolytic digestive enzymes called lysozymes
  • They break down worn out components of the cell or digest invading cells
30
Q

Function of Mitochondria

A
  • Site of aerobic respiration
  • As a result of respiration, they release ATP (source of energy for use at cellular level)
31
Q

Function of the Ribosomes:

A

These are where proteins are made and they assemble amino acids into proteins in chains using mRNA.

32
Q

Structure of Ribosomes:

A
  • Made from RNA and protein
  • Not membrane bound
  • Very small organelles: 22nm in diameter
  • Found free floating in the cytoplasm or attached to the Rough ER
33
Q

Structure of the Smooth Endoplasmic Reticulum:

A

Similar to RER but lacks ribosomes - it’s a system of interconnected tubules.

34
Q

Structure of the Rough Endoplasmic Reticulum:

A

Stacks of membrane bound sacs which form sheets called cisternae. Attached to the nucleus and covered in ribosomes. It consists of an interconnected system of flattened sacs.

35
Q

Function of Nucleus:

A
  • Controls all the activity of the cell
  • Where the DNA of the cell is stored, replicated and copied into RNA (transcribed)
  • The nucleus is attached to the Rough ER so the mRNA can easily get to ribosomes.
35
Q

Parts of the nucleus:

A
  • Double Nuclear Envelope
  • Nuclear Pores
  • Nucleolus
  • Chromatin
36
Q

What is the nucleolus?

A

Part of the nucleus - Site of ribosome production. Composed of RNA and proteins.

37
Q

What are microfilaments?

A

Fibres made from the protein actin. They are responsible for movement of the cell and cytoplasm during cytokinesis.

37
Q

What are the Nuclear Pores?

A

Part of the nucleus that allows molecules to enter (e.g. nucleotides for DNA replication) and leave the cell e.g. mRNA leaves the cell.

38
Q

What are microtubules?

A

Formed by the globular protein tubulin. They polymerise to form tubes that determine the shape of the cell. They also act as tracks for organelles moving around the cell.

39
Q

Function of the Cytoskeleton

A
  • Provides mechanical strength to cells
  • Aiding transport within cells
  • Enabling cell movement
40
Q

The 3 structural components of the cytoskeleton:

A
  • Microfilaments
  • Microtubules
  • Intermediate fibres

Biology A-Level (5 decks)

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