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OCR A-LEVEL Biology > Module 2 Section 1 - Cell Ultrastructure > Flashcards

Module 2 Section 1 - Cell Ultrastructure Flashcards

1
Q

What are the 3 structural components of a cytoskeleton

A

1) Microfilaments
2) Microtubules
3) Intermediate Fibres

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2
Q

What are the functions of a Cytoskeleton

A
  • To provide mechanical strength
  • Aiding transport with cells
  • Enabling Cell movement
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3
Q

what are microfilaments made of

A

the protein Actin

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4
Q

what is the microfilament of the cytoskeleton responsible for

A

movement of the cell and cytoplasm during cytokinesis

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5
Q

what are microtubules made of

A

the protein tubulin

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6
Q

microtubules can also act as…

A

tracks for organelles moving around the cell

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7
Q

intermediate fibres give…..

A

strength to cells and help maintain integrity

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8
Q

what is the structure of the nucleus

A
  • Double nuclear envelope
  • nuclear pores
  • nucleolus
  • chromatin
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9
Q

what is the double nuclear envelope

A

a double membrane which separates the nucleus and prevents damage. protects the DNA

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10
Q

what are nuclear pores

A

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

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11
Q

what is the nucleolus

A

site of ribosome production, composed of RNA and proteins

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12
Q

what is chromatin

A

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

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13
Q

what is the function of the nucleus

A

-controls all the activity of the cell
-where genetic code (DNA) of the cell is stored, replicated, and copied into RNA
- the nucleus is attached to the rough ER (endoplasmic reticulum) so the mRNA can esily get to ribosomes

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14
Q

what is the structure of rough endoplasmic reticulum (rough ER)

A

-stacks of membrane bound sacs which form sheets called cisternae
-it is also attached to nucleus and covered with ribosomes

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15
Q

what is the function of the rough ER

A

site of protein synthesis

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16
Q

what is the structure of the smooth ER

A

similar to rough ER but it lacks ribosomes - is a system of interconnected tubules

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17
Q

what is the function of the smooth ER

A

responsible for carbohydrate & lipid synthesis as well as storage

18
Q

what is the structure of ribosomes

A
  • a 2 subunit organelle
  • made from RNA and protein
  • not membrane bound
  • about 22nm in diameter
  • found free floating in the cytoplasm or attached to the rough ER
19
Q

what is the function of ribosomes

A
  • this is where protein is made
  • they assemble amino acids into proteins in chains using mRNA
20
Q

what is the structure of the mitochrondria

A

-oval shaped
-surrounded by 2 membranes
- inner membrane called cristae which increases the surface area
- the solution inside is called matrix which contains enzymes for respiration

21
Q

why is mitochrondrial dna important

A

it enables mitochrondrion to reproduce and create enzymes

22
Q

what is the function of mitochrondria

A
  • site of aerobic respiration which releases atp (energy carrier in cells)
23
Q

what is the strucutre of the golgi apparatus

A
  • stacks of flattened, membrane bound sacs (cisternae)
  • these are contiously formed from the ER at one end and budding off as golgi vesicles at the other
24
Q

what is the function of the golgi appartus

A
  • allows internal transport
  • recieves proteins from the rough ER
  • modifies and processes molecules (e.g. lipids and proteins) and packages them into vesicles
  • these may be secretory vesicles (leaving the cell) or lysosomes (stay in the cell)
  • make lysosomes
  • lipid synthesis
25
Q

what is the structure of lysosomes

A

they are spherical sacs surrounded by a membrane

26
Q

what is the function of the lysosomes

A
  • they contain powerful digestive enzymes called lysozymes their role is to break down worn out components of the cell or digest invading cells
27
Q

what is the structure of the centrioles

A
  • a component of the cytoskeleton, composed of many microtubules
  • small hollow cylinders that occur in pairs next to the nucleus in animal cells
  • each centriole contains a ring of 9 microtubules
28
Q

what is the function of centrioles

A

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

29
Q

what is the strucutre of the 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 2 microtubules in the middle
  • known as a 9+2 arrangement which allows movement
30
Q

what is the function of the cilia

A
  • sensory function (e.g. nose), beat creating a current to move fluid/muscous/objects
  • for locomotion
31
Q

what is the structure of the 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
32
Q

what is the function of the flagella

A

-enables cell mobility
-the microtubules contract to make the flagellum
-propel the cell forward

33
Q

what is the structure of the chloroplast (plant cells only)

A

double membrane which encloses the stroma
stroma contains: strach grains, lipid stores, DNA, RNA, Ribosomes
series of membrane-bound flattened sacs called thylakoids in the stroma.
stacked thylakoids are called grana which is connected by lamellae
the grana contain chlorophyll

34
Q

what is the function of the chloroplast - plant cell only

A

photosynthesis reactions

35
Q

what is the structure of the cell surface membrane

A

a phospholipid bilayer (phosphorus and lipid)
composed of proteins and lipids

36
Q

where is the cell surface membrane found

A

on the surface of animal cells
inside the cell wall of plant and prokaryotic cells

37
Q

what is the function of the cell surface membrane

A

it regulates the movement of substances in and out of the cell
contains receptor molecules that allow it to respond to chemical like hormones

38
Q

what is the structure of the cellulose cell wall

A

composed of b-cellulose microfibrils - complex carbohydrate
cell wall fully permeable to substance
thin layer called middle lamella marks the boundary between adjacent cell walls and ‘cements’ adjacent cells together

39
Q

what is the function of the cellulose cell wall

A

gives plant mechanical strength
gives plant cell support and it’s shape
contents of plant cell can ‘push’ against the cell wall (turgid cell). this gives the cell good support

40
Q

what is the structure of large permanent vacuole

A

single membrane bound - called tonoplast
contain cell sap
selectively permeable barrier

41
Q

what is the function of the large permanent vacuole

A

stroes cell sap
support herbaceous plants by make cells turgis
hepls maintain shape and mains turgor pressure
sugar and amino acids act as temporary food stroe

OCR A-LEVEL Biology (48 decks)

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