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Science - Biology - OCR: A(S) Level > Cell Biology > Flashcards

Cell Biology Flashcards

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1
Q

What is an organelle?

A

An organelle is a smaller, specialised compartment/structure within a cell to carry out a particular function.

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2
Q

What is a cell and how did we find out about them?

A

Cells are the basic structural unit of all organisms, we only found out about them in the mid 1800s with the creation of the light microscope.

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3
Q

Who did this enable and how?

this = the light microscope

A

This enabled Robert Hooke due to the light microscope having a higher magnification than the naked human eye to view cells and some larger structures inside more individually.

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4
Q

What is cell theory?

A
  • Plant & Animal tissue is comprised of cells
  • Cells are the basic unit of all life
  • Cells only develop from existing cells
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5
Q

What is a Eukaryotic cell? Give an example.

A

‘True nucleus’ - DNA is contained within a nucleus. TYPICALLY larger than a prokaryotic cell.

REMEMBER: EUkaryotic - EU is large!

An example is a plant, fungal or animal cell.

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6
Q

What is a Prokaryotic cell? Give an example.

A

‘Before nucleus’ - DNA is NOT contained in a nucleus. TYPICALLY smaller than a eukaryotic cell.

REMEMBER: PROkaryotic - [Pro]tests to be heard as you’re small!

An example is a bacterial cell.

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7
Q

Define compartmentalisation.

A

When organelles have their own individual & distinct membranes and environments within a cell to allow for different reactions to take place (as they may need different conditions).

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8
Q

What is the sum of all reactions (in a cell) called? Examples include reactions for building up and breaking down molecules.

A

(Cell) metabolism/(Cell) metabolic reactions.

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9
Q

What is the ultrastructure of a cell?

A

(Smaller) Structures of a cell only available to see under an electron microscope.

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10
Q

Why is an electron microscope better than a light microscope (links to Microscopy!)?

A
  • Higher magnification (from shorter wavelength (thus higher frequency))
    Due to this, the beams of electrons can pick up smaller structures inside cells such as the mitochondria.
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11
Q

List all sub-cellular structures/organelles in a plant cell.

A
  • Mitochondria
  • Golgi body/apparatus
  • Nucleolus
  • Nucleus
  • Nuclear envelope (+ nuclear pores)
  • Centrioles (+ Microtubules)
  • Cytoplasm
  • Ribosomes
  • Plasma (Cell Surface) membrane
  • Smooth Endoplasmic reticulum
  • Rough Endoplasmic reticulum
  • Golgi vesicles
  • Lysosome
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12
Q

What are extra organelles in a plant cell?

A
  • Cell wall
  • Chloroplast
  • Plasmodesmata
  • Amyloplast
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13
Q

What is the structure of the Plasma (Cell surface) membrane?

A
  • Phospholipid bilayer
  • Contains proteins/protein channels
  • Hydrophobic exposed heads
  • Hydrophilic hidden tails
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14
Q

What is the function of the Plasma (cell surface) membrane?

A
  • Surrounds external surface of cell
  • Regulates movement of molecules in/out of cell
  • Partially permeable (Osmosis!)
  • Selectively permeable
  • Barrier between cell and external environments (which may disrupt cell functions otherwise)
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15
Q

What is the structure of the cytoplasm(/cytosol), and why is it important?

A
  • Jelly-like substance/liquid
  • Mostly water (+ filled with proteins)

Being mostly water is important as it can act as a solvent (so substances dissolve) to facilitate many cell reactions (its function).

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16
Q

What is the function of the cytoplasm?

A
  • Organelles sit in the cytosol making it cytoplasm
  • Site of many (cell) metabolic reactions, such as anaerobic respiration
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17
Q

What is the structure of the Nucleus?

A
  • Surrounded by nuclear envelope
  • Nuclear pores in the nuclear envelope (allow for substances, such as ribosomes or RNAs in/out)
  • DNA wound around histone proteins, turned to chromatin, then chromosomes (condensed/coiled DNA) to allow lots of DNA to fit in the nucleus
  • Contains the nucleolus, a dark staining region with lots of condensed DNA
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18
Q

What is the function of the Nucleus?

A
  • Control cell activity
  • Nuclear envelope seperates nucleus & cytoplasm, regulates movement of molecules in/out of the nucleus
  • Nuclear pores allow molecules to move in/out the nucleus (e.g., mRNA leaves through the nuclear pores in the nuclear envelope)
  • Contains DNA
  • Nucleolus -> Ribosome synthesis
19
Q

What is the cytoskeleton?

A

Present throughout the cytoplasm of all eukaryotic cells. A network of fibres necessary for the shape & stability of a cell. It’s also responsible for holding organelles in place as well as cell movement/organelle movements within cells.

20
Q

What are the 3 main cytoskeleton fibres?

A
  • Microfilaments
  • Microtubules
  • Intermediate Filaments/Fibres
21
Q

What protein makes up MICROFILAMENTS?

A

Actin

22
Q

What protein makes up MICROTUBULES?

A

Tubulin

23
Q

What are Intermediate Filaments made up of?

A

Rigid fibres/Fibrous proteins that don’t change length.

24
Q

What do microfilaments do in the cytoskeleton of a cell?

A

Contractile fibres that are responsible for movement of the plasma membrane & cytokinesis (division of cytoplasm in a Eukaryotic cell to produce 2 daughter cells).

25
Q

What do microtubules do in the cytoskeleton of a cell?

A

They can polymerise (add to end) & depolymerise (take off end) to change length. Forms a scaffold structure to determine shape of cell. Acts as tracks for movement of organelles around. Become spindle fibres, involved in movement of chromosomes in cell division.

26
Q

What do the intermediate filaments in the cytoskeleton do in a cell?

A

Give mechanical strength to cells & helps maintain integrity (strong & set).

27
Q

What are Centrioles made of?

A

Microtubules

28
Q

What is the centrosome, and where is it found?

A

It is a pair of Centrioles that are perpendicular to each other. Often found near the nucleus.

29
Q

What are the Centrioles?

A

A component of the cytoskeleton in most eukaryotic cells, except flowering plants and fungi.

30
Q

What do the Centrioles/Centrosome do?

A

Involved in the assembly & organisation of spindle fibres during cell division.

31
Q

What is the structure of the mitochondria?

A
  • Sausage shaped
  • Surrounded by an envelope (double membrane)
  • Inner membrane is folded into cristae
  • Matrix contains mitochondrial DNA/traces of maternal DNA

https://cdn.savemyexams.co.uk/cdn-cgi/image/w=960,f=auto/uploads/2021/03/Mitochondria-Structure.png

32
Q

What is the function of the mitochondria?

A

Provide/Release energy via aerobic respiration (production of ATP to supply the cell with energy)

Enzymes are needed (as biological catalysts) and are found in the cristae

33
Q

What is the structure of vesicles?

A

A sac surrounded by a single membrane.

Due to being in cytosol (aqueous), the substances making up its membranes react in a unique way to form a circular shape with hydrophilic heads out and hydrophobic tails in.

34
Q

What is the function of the vesicles?

A

Storage and transport of materials around & out of cells.

35
Q

What is the function of the transport vesicles?

A

Vesicles containing molecules for transport around the cell.

36
Q

What is the function of the secretory vesicles?

A

Vesicles containing molecules to the plasma membrane to be released from the cell.

37
Q

What is the structure of a Lysosome?

A
  • Specialised vesicles (sacs)
  • Contain a specific type of molecule called hydrolytic (digestive enzymes)
38
Q

Why is it important that lysosomes are compartmentalised? (Have their own membrane within the cell)

A

Their degrading of other substances must be contained within them to avoid the whole cell being degraded when it’s not waste at that point.

39
Q

How are lysosomes different from vesicles under electron micrographs?

A

Appear larger and darker than vesicles.

40
Q

What is the function of the Lysosome?

A

Degrade/break down waste materials, including worn out organelles & pathogens that have invaded the body

41
Q

What is the structure of SMOOTH Endoplasmic Reticulum?

A
  • Network of membranes arranged into flattened sacs called cristae
  • Normally found further away from than nucleus (than the RER)
  • Surface is smooth as it has nothing attached to it (e.g., no ribosomes)
42
Q

What is the function of the SMOOTH Endoplasmic Reticulum?

A

Synthesis & storage of lipids and carbohydrates

43
Q

What is the structure of the ROUGH Endoplasmic Reticulum?

A
  • Network of flattened membranous sacs (cristae)
  • These are an extension of the nuclear envelope so are found closer to the nucleus
  • Surface is rough as it is covered in ribosomes (important in protein synthesis)
44
Q

What is this function of the ROUGH Endoplasmic Reticulum?

A

Synthesis, folding & transport of proteins

Science - Biology - OCR: A(S) Level (1 decks)

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