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Biology AS > 2.4 Eukaryotic cell structure > Flashcards

2.4 Eukaryotic cell structure Flashcards

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1
Q

What are the 2 basic types of cells?

What is the difference between these cells?

A

Prokaryotes and Eukaryotes

PK:

  • Simple undivided internal structure of only a cytoplasm
  • Single celled

EK:

  • Make up multicellular organisms (animals, plants, fungi)
  • Complex internal structure (membrane-bound nucleus, membrane-bound organelles)
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2
Q

What does metabolism involve?

A

Synthesis (anabolism) and break down of molecules

*(reactions take place in cytoplasm)

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3
Q

Describe the properties and function of membranes

A
  • Selectively permeable
  • Separate cytoplasm from external environment
  • Control movement of substances in/out of cell
  • Quite fragile
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4
Q

Common features in all eukaryotic cells

*Refer to Figure 3 on p.g. 27

A
  • Microtubule network
  • Vesicles
  • Nucleolous
  • Nucleus
  • Golgi apparatus
  • Cytosol
  • Ribosome
  • Centriole
  • Cell-surface membrane
  • RER (rough endoplasmic reticulum)
  • SER (smooth endoplasmic reticulum)
  • Cytoskeleton
  • Mitochondria
  • Secretory vesicles
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5
Q
  1. What does the nucleus contain?

2. What is the function of this?

A
  1. Contains genetic info in the form of DNA

2. DNA directs synthesis of proteins - controls metabolism as many proteins are enzymes

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6
Q

What is the nucleus in?

A

A double membrane - nuclear envelope

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7
Q

What is the function of the nuclear envelope?

A

To protect the nucleus from damage in the cytoplasm

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8
Q

What does the nuclear envelope contain?

A

Nuclear pores

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9
Q

What is the function of nuclear pores?

A

Allow substances to move in and out of the nucleus

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10
Q

How does DNA leave the nucleus?

A

DNA too big to leave nucleus - transcribed into smaller RNA molecules; exported via nuclear pores

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11
Q

How is chromatin formed?

A

When DNA associates with histones (proteins)

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12
Q

How are chromosomes formed?

A

Chromatin coils + condenses

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13
Q

What is the nucleolus?

What is its function?

A
  • Area within nucleus
  • Made up of proteins and RNA

-Produces ribosomes

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14
Q

What is RNA in the nucleolus used for?

A

To produce ribosomal RNA (rRNA), which is then combined w/ proteins to form ribosomes

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15
Q

Describe the structure of the mitochondria

A
  • Double membrane
  • Inner membrane highly folded to form cristae
  • Fluid interior = matrix
  • Contain DNA - mitochondrial DNA (mtDNA)
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16
Q

What is the function of the mitochondria?

A
  • Site of cellular respiration
  • Stored energy made available by producing ATP
  • Amount reflects how much energy the cell uses - active cells = lots
  • Membrane forming cristae contains enzymes for aerobic respiration
  • Can produce own enzymes + reproduce on its own
17
Q

What are vesicles? What are they used for?

A
  • Membranous sacs w/ storage + transport roles
  • Consist of single membrane w/ fluid inside
  • Used to transport materials inside cells
18
Q

What are lysosomes?

A

Specialised vesicles that contain hydrolytic enzymes

19
Q

What is the function of lysosomes

A
  • Break down waste in cells
  • Break down pathogens ingested by phagocytes
  • Involved in programmed cell death (apoptosis)
20
Q

What is the cytoskeleton? Where is it?

A
  1. Network of fibres required for shape and stability of
    the cell
  2. Present throughout cytoplasm of eukaryotes
21
Q

What is the function of the cytoskeleton?

A
  • Hold organelles in place

- Controls cell movement

22
Q

What are the 3 components of the cytoskeleton?

A

Microfilaments
Microtubules
Intermediate fibres

23
Q

What are microfilaments?

A

Contractile fibres made from actin
Responsible for cell movement and cell contraction during cytokinesis
*(Cytokinesis - when cytoplasm of 1 cell divides to form 2 daughter cells)

24
Q

What are microtubules?

A
  • Determine cell’s shape

- Help move organelles - Act as path for movement of organelles

25
Q

What are spindle fibres?

A
  • Made up of microtubules

- Role in chromosome separation during cell division

26
Q

What is the function of intermediate fibres?

A
  • Give mechanical strength to cells

- Help maintain cell’s integrity

27
Q

What are centrioles?

A
  • Components of cytoskeleton in eukaryotes (not flowering plants or fungi)
  • Composed of microtubules
  • 2 centrioles = centrosome
  • Centrosome - involved in organisation of spindle fibres during cell division
28
Q

What is the flagella and cilia? Compare them

A

Extensions protruding from some cells

-Flagella = longer but cilia = present in greater numbers

29
Q

What are flagella used for?

A
  • Enable cell motility

- Sensory organelles detecting chemical changes in cell’s env.

30
Q

What 2 types can cilia be? Elaborate on them

A

Stationary:

  • On surface of cells
  • Roles in sensory organs e.g. nose

Mobile:
- Beat in rhythmic manner, creating current = causes adjacent fluid to move
E.G. In trachea; move mucus away from lungs to keep air passage clean
In fallopian tubes to move egg cells from ovary to uterus
*(Cilia are made up of microtubules)

31
Q

What is the endoplasmic reticulum?

A

A network of membranes enclosing flattened sacs called cisternae
-Connected to outer membrane of nucleus

32
Q

What is the role of the smooth endoplasmic reticulum (SER)?

A

Synthesis + storage of lipids + carbs

33
Q

What is the role of the rough endoplasmic reticulum

(RER)?

A
  • Has ribosomes bound to surface

- Synthesis + transport of proteins

34
Q

Where can ribosomes be found?

A
  • Free-floating in cytoplasm

- Attached to RER

35
Q

What are ribosomes?

A
  • No membrane
  • Constructed of RNA made in nucleolus
  • Site of protein synthesis
36
Q

What is the golgi apparatus?

A
  • Similar structure to SER
  • Compact structure formed of cisternae
  • No ribosomes
37
Q

What is the function of the golgi apparatus?

A
  • Modifying proteins + packing them into vesicles:
    Secretory vesicles - if protein needs to leave cell
    Lysosomes - if protein stays in cell
38
Q

Describe the 5 stages of protein production

A

1) Proteins synthesised on ribosomes bound to RER
2) Pass into cisternae + packaged into transport vesicles
3) Vesicles containing the synthesised proteins move to Golgi apparatus via cytoskeleton
4) Vesicles fuse with Golgi apparatus - proteins enter.
Proteins are structurally modified before leaving Golgi
apparatus
5) Secretory vesicles carry protein, vesicle moves to + fuses with plasma membrane to release contents via exocytosis. Some vesicles form lysosomes - these contain enzymes for use in cells

Biology AS (148 decks)

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