Biology > 2. Eukaryotic Cells > Flashcards

2. Eukaryotic Cells Flashcards

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1
Q

Define cell ultrastructure

A

Internal structure of a cell (organelles present AS WELL AS structure of the organelles)

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2
Q

Define eukaryotic cells

A

A larger cell with a nucleus and membrane-bound organelles in its cytoplasm

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3
Q

Examples of eukaryotic cells

A

All animal & plant cells
Fungi
Protoctists

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4
Q

Define prokaryotic cells

A

A smaller cell that doesn’t have a true nucleus or membrane-bound organelles

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5
Q

Examples of prokaryotic cells

A

All bacteria

Archaea

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6
Q

Examples of membrane-bound organelles

A

Mitochondria
Chloroplasts
Vacuoles

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7
Q

4 differences between plant and animal cells

A
  1. Plant cells have a cell wall made of cellulose
  2. Plant cells have a large permanent vacuole containing cell sap
  3. SOME plant cells have chloroplasts containing chlorophyll
  4. Plant cells store carbohydrates as starch; glycogen for animals
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8
Q

What does a cell surface membrane look like at very high magnification?

A

Two dark lines separated by a pale area (plasma membrane)

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9
Q

4 functions of cell surface membrane

A
  1. Controls what enters & leaves cell
  2. Cell recognition (e.g. for immune system)
  3. Adhesion (cells sticking together - important in tissues in multicellular organisms)
  4. Signalling (e.g. receptors on surface)
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10
Q

What is the cell surface membrane composed of

A

A phospholipid bilayer

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11
Q

How wide is the cell surface membrane?

A

Very thin (10 nm)

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12
Q

Cytoplasm function

A

Contains organelles & enzymes for reactions

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13
Q

Size of nucleus

A

10-20 micrometres in diameter (largest organelle!)

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14
Q

Structure of nucleus

A

Double membrane (nuclear envelope) with nuclear pores (100nm diameter) that allows movement of molecules such as mRNA

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15
Q

What is inside the nucleus?

A

Nucleoplasm - granular, jelly-like material

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16
Q

How do chromosomes behave?

A

Visible during cell division but at other times are dispersed as chromatin (unravelled chromosome)

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17
Q

The outer membrane of the nucleus is…

A

Continuous with the rough endoplasmic reticulum

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18
Q

Functions of the nucleus

A
  1. Enables protein synthesis through production of mRNA and tRNA
  2. Retains genetic material as chromosomes
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19
Q

Structure of nucleolus

A

One or more darkly staining spherical areas within the nucleus

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20
Q

Is the nucleolus membrane bound?

A

NO

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21
Q

Function of nucleolus

A

Site of manufacture of ribosomal RNA and assembly of ribosomes

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22
Q

Size of ribosomes

A

around 20 nm diameter (smallest organelle)

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23
Q

Where are ribosomes

A

Free in cytoplasm or bough to rough ER (in eukaryotes)

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24
Q

Are ribosomes surrounded by a membrane?

A

NO

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25
What are ribosomes made of
rRNA and protein
26
Function of ribosomes
Site of protein synthesis
27
Size of ribosomes
80S in eukaryotes | 70S in prokaryotes (slightly smaller)
28
Ribosomes have...
a large and small subunit
29
Structure of rough endoplasmic reticulum
System of membrane bound, flattened sacs (channels) called cisternae
30
The cisternae are...
interconnected throughout the cell
31
Why is the rough ER rough
It's studded with ribosomes
32
Proteins and the rough ER
Proteins are synthesised on the ribosomes on the rough ER. They are then passed into the cisternae and carried by vesicles to the Golgi
33
Which cells have the most rough endoplasmic reticulum?
1. Pancreatic cell - produces & secretes insulin 2. Cells lining stomach - produce & secrete pepsin 3. Cells in salivary glands - produce & secrete amylase 4. Pituitary glands - hormones (FSH & LH) Generally cells that produce lots of protein
34
Singular of cisternae
cisterna
35
Structure of Golgi apparatus
A stack of flattened membranous sacs called cisternae
36
What type of structure does a Golgi have
Dynamic structure: vesicles join from the ER and bud off to form secretory vesicles and lysosomes
37
Function of Golgi
Sorting, modifying and packaging of polymers (e.g. proteins) for secretion
38
How are proteins secreted in a cell?
1. Protein made on ribosomes enter rough ER 2. Protein moves through ER assuming three-dimensional shape en route 3. Vesicles pinched off rough ER contain the protein 4. Vesicles from rough ER fuse to form flattened sacs of Golgi apparatus 5. Proteins modified within Golgi 6. Vesicles pinched off Golgi contain modified protein 7. Vesicle fuses with cell surface membrane releasing protein
39
What is the Golgi vesicle?
A small, spherical sac of cytoplasm enclosed by single membrane. Part of Golgi apparatus.
40
What are lysosomes?
* Vesicles containing up to 50 different hydrolytic enzymes (e.g. proteases, lipases & lysozymes) * They remain inside the cell!
41
What do lysozymes do?
Break down bacterial cell walls
42
What do lysosomes do?
*  Fuse with phagocytic vesicles to digest contents in a phagocyte * Digest old dead cells (autolysis) and worn out organelles
43
Function of smooth endoplasmic reticulum
Synthesis, storage and transport of lipids and carbohydrates
44
Compare structure of smooth ER to rough ER and Golgi (apart from having no ribosomes)
Less compact
45
Why is the smooth ER smooth?
No ribosomes at all
46
What does smooth ER look like under a microscope?
Lots of little "bubbles" - see OneNote
47
How long are mitochondria?
Around 1-10 micrometres
48
What shape are mitochondria?
Rod shaped or cylindrical
49
Describe membrane of mitochondria
* Double membrane | * Inner membrane folded into extensions called cristae (large surface area for enzymes involved in aerobic respiration)
50
What does interior of mitochondria contain?
Aqueous solution of metabolites and enzymes (e.g. those involved in Krebs cycle), called the matrix
51
What does the matrix contain?
Its own DNA and ribosomes
52
What is the chloroplast?
Site of photosynthesis in green plants and photosynthetic protoctists
53
How long is a chloroplast?
2-10 micrometres (considered large)
54
What is the chloroplast surrounded by?
An envelope (double membrane - outer and inner)
55
The chloroplast has a fluid-filled ____ called the ____
matrix; stroma
56
What does the stroma contain?
Starch grains
57
What are thylakoids?
Disc-like structures that have chlorophyll within their membrane
58
A stack of thylakoids is a...
granum
59
Plural of granum
grana
60
What do some thylakoids have?
Tubular structures connecting with an adjacent granum
61
Chloroplasts have their own...
DNA and ribosomes
62
Chloroplasts adaptations (3)
1. Thylakoid membranes of grana create large SA for attachment of chlorophyll & enzymes involved in 1st stage of photosynthesis 2. Stroma contains enzymes required for 2nd stage 3. Contains DNA & ribosomes: can quickly make proteins (enzymes) required in photosynthesis
63
What is the vacuole?
A fluid-filled sac surrounded by a single membrane - the tonoplast
64
What does the vacuole contain?
A solution of mineral salts, sugars, amino acids, wastes and coloured pigments
65
What does the vacuole do?
Supports plants by making cells turgid
66
What do sugars and amino acids in the vacuole act as?
A temporary food store
67
What else does the vacuole contain?
Pigments (e.g. anthocyanins) - used to attract insects
68
Structure of plant cell walls
Cellulose microfibrils laid down at different angles and embedded in a polysaccharide matrix
69
Plant cell wall function
Provides mechanical strength and support, and stops cells bursting.
70
Are plant cell walls freely permeable?
Yes :)
71
Middle lamella
Marks boundary between adjacent cell walls & cements cells together
72
Plasmodesmata
Cytoplasmic connections between plant cells through gaps in their cell walls
73
What are fungi cell walls made of?
Mixture of chitin and glycoproteins
74
What are algae cell walls made of?
Either cellulose or glycoproteins, or a mix of both
75
Does the Golgi contain DNA
NO
76
Does the smooth or rough ER contain DNA
NO
77
Do the vesicles contain 70S ribosomes
NO
78
Do the ER contain 70S ribosomes
NO
79
Do mitochondria contain 70S ribosomes
YES
80
Do chloroplasts contain 70S ribosomes
YES
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