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A Level Biology OCR A > Cell Structure > Flashcards

Cell Structure Flashcards

(72 cards)

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1
Q

What are the features of eukaryotic cells?

A
  • cytoplasm
  • plasma membrane/ cell surface membrane
  • membrane bound organelles
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2
Q

Define membrane bound organelles

A

Organelles which are covered by a membrane to keep them separate from the rest of the cell

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3
Q

State the membrane bound organelles present in a eukaryotic cell

A
  • nucleus
  • rough and smooth endoplasmic reticulum
  • golgi apparatus
  • mitochondria
  • lysozymes
  • cilia and undulipodia
  • chloroplasts
  • vacuole
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4
Q

What sub-cellular structures contain their own DNA?

A
  • nucleus
  • mitochondria
  • chloroplasts
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5
Q

State the different parts that make up the nucleus

A
  • nuclear envelope
  • nucleolus
  • chromatin
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6
Q

What is the function of the nuclear envelope?

A
  • Separates the contents of the nucleus from the rest of the cell
  • double membrane, contains pores
  • at points wherein the inner and outer membranes fuse, dissolved substances can pass through
  • pores enable larger substances (such as mRNA and hormones) to enter and leave the nucleus
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7
Q

What is the function of the nucleolus?

A
  • ribosomes are made here
  • no membrane around it
  • contains RNA
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8
Q

What is the function of the chromatin?

A

Genetic material (DNA & histone proteins) condense to chromosomes during division

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9
Q

What is the difference between chromatin when the cell is dividing and when its not dividing?

A
  • when cell is not dividing, chromatin is spread out or extended
  • when cell is about to divide, chromatin condenses and coils tightly into chromosomes
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10
Q

State the components of the rough endoplasmic reticulum

A
  • cisternae
  • ribosomes
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11
Q

What are the cisternae?

A

Series of flattened sacs

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12
Q

What is the function of cisternae?

A

Form channels to transport substances

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13
Q

What is the function of the ribosomes?

A
  • protein synthesis occurs and proteins pass through the cisternae to Golgi Apparatus OUT of the cell
  • RER has a large surface area for ribosomes
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14
Q

What is the difference between the rough ER and the smooth ER?

A

Rough ER has ribosomes on its surface, whereas smooth ER does not

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15
Q

What is the function of the cisternae in the smooth ER?

A
  • continuous with nuclear membrane to transport lipids
  • contains enzymes that catalyse reactions involved in lipid metabolism and synthesis, and carbohydrate metabolism
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16
Q

Describe the Golgi Apparatus

A

Series of fluid filed flattened and curved sacs, with vesicles surrounding the edges

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17
Q

What are the components of the Golgi Apparatus?

A
  • stack of membrane flattened sacs
  • vesicles
  • secretory vesicles
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18
Q

What is the function of the stack of membrane bound flattened sacs?

A

Proteins modified by adding sugar to make glycoproteins or lipids to make lipoproteins

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19
Q

What is the function of the vesicles?

A

contains proteins that fuse with the Golgi apparatus

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20
Q

What is the function of secretory vesicles?

A

Take modified proteins out of the golgi apparatus

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21
Q

What is the overall function of the golgi?

A

Processes and packages proteins and lipids

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22
Q

What is the difference between secretory vesicles and transport vesicles?

A
  • secretory vesicles store and release materials into the cell or to the extracellular environment
  • whereas transport vesicles move materials within the cell
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23
Q

What are the components that make up mitochondria?

A
  • outer membrane
  • inner membrane that folds into cristae
  • inner part of mitochondrion is a fluid filled matrix
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24
Q

What is the function of mitochondria?

A

It is the site of ATP production during aerobic respiration

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25
Why can mitchondria come in different shapes?
Depends on how the cell has been cut, for example if cut through the top middle the mitochondria may appear circular, but if cut through the side middle, the mitochondria may appear rod-shaped
26
What are the different shapes that mitochondria can come in?
- spherical - rod-shaped - branched
27
What are **lysozymes**?
- **small bags** formed in the golgi - surrounded by a **single membrane**
28
What is the function of a **lysozyme**?
*Contains powerful **hydrolytic enzymes** to digest and engulf substances/ organelles*
29
What are **cilia and undulipodia**?
Protrusions from the cell and are surrounded by the cell membrane
30
What is the function of **cilia**?
*To move or monitor substances*
31
What is the function of **undulipodia**?
*Enables sperm to move*
32
What is the function of a **singular cillium**?
- acts as an antenna - *contains receptors that can detect movement + signals about the immediate environment*
33
What are the components present in a **chloroplast**?
- thylakoids - stroma
34
35
What is a **thylakoid**?
- Stacks of flattened membrane sacs, containing **chlorophyll** - each stack is called a **granum**
36
What is the function of a **thylakoid**?
*First stage of photosynthesis occurs here*
37
What is the first stage of photosynthesis?
Light energy is trapped + used to make ATP
38
What is the **stroma**?
Fluid filled matrix
39
What is the function of a **stroma**?
*Second stage of photosynthesis occurs here*
40
What is the second stage of photosynthesis?
Hydrogen reduces carbon dioxide to make carbohydrates
41
What are the components of a **vacuole**?
- tonoplast - cell sap
42
What is a **tonoplast**?
Single membrane, contains fluid
43
What are the functions of a **tonoplast**?
*Filled with water and solutes + maintains cell stability (pushes against cell wall when full, making cell turgid)*
44
What is the function of **cell sap**?
*Makes cell stable*
45
Describe the interrelationship between the organelles involved in the production and secretion of proteins
1. Nucleus **releases** mRNA 2. mRNA **translated** by the ribosome onto the rough ER 3. Proteins pass into the cisternae of the RER 4. Vesicles break off the cisternae 5. Vesicle carries protein to golgi and **fuses** with it 6. Proteins are modified by adding carbs/ lipids 7. Secretory vesicles break away from Golgi and move to cell membrane 8. SV **fuses** with cell membrane 9. Proteins released by **exocytosis**
46
What are the **non membrane bound organelles**?
- ribosomes - centrioles - cellulose cell wall
47
What are the components of **ribosomes**?
Made of a large subunit and a small subunit
48
Where are **ribosomes made**?
Made in the **nucleolus** and combine in the **cytoplasm**
49
How large are eukaryotic ribosomes?
20nm in diameter
50
Where are **ribosomes found**?
- attached to the RER - some stay in the cytoplasm
51
What is the function of the **ribosome**?
*Assemble proteins*
52
What is the difference between the ribosomes in the **cytoplasm vs the RER**?
- **RER**: synthesis proteins that will be exported out of the cell - **cytoplasm**: site of assembly of proteins for within the cell
53
What are **centrioles**?
2 bundles of microtubules at right angles to each other
54
What are **microtubules** made of?
Tubulin
55
What is the function of a **centriole**?
- *Spindle made from these during cell division + chromosomes attach to be pulled* - forms **cilia and undulipodia**
56
How do centrioles form cilia and undulipodia?
- microtubules line up at the edge of the cell - and spout outwards from each centriole, forming a cilium or undulipodium - **this only occurs for specialised cells**
57
What subcellular structures are exclusive to plant cells?
- large **permanent** vacuole - chloroplasts - cellulose cell wall
58
What subcellular structures are exclusive to animal cells?
Centrioles
59
Define **cytoskeleton**
A **dynamic** network of protein structures within the cytoplasm
59
What is the function of a **cellulose cell wall**?
- *provide strength and support* - *maintain cell shape* - *contribute to the strength and support of the **whole plant*** - ***permeable***
60
What are the components of the **cytoskeleton**?
- **tubulin** microtubules form a track (continuously changing) to move organelles using **motor proteins** - microfilaments made from **actin** contribute to the stability and movement of the whole cell - intermediate filaments anchor nucleus and stabilise tissues
61
What are the **motor proteins** present in the cytoplasm and what is their **function**?
- myosins, kinesins, dyneins - move substances around the cytoskeleton - they are also **enzymes** and have a site that binds to and enables **hydrolysis** of ATP as their energy source
62
What is the **function** of a cytoskeleton?
- cell support/ stability/ scaffolding/ maintaining the shape - movement of cilia/ flagella/ undulipodia or use of flagellum/ undulipodium to move - change shape of cell - organelles moved - movement of chromosomes/ mRNA/ vesicles - formation of spindle - mainly: **providing mechanical strength to cells, aiding transport within cells and enabling cell movement**
63
What are the similarities between **prokaryotic and eukaryotic cells**?
- contain cytoplasm - plasma membrane - non membrane bound organelles - contain DNA & RNA
64
What are th differences between **prokaryotic and eukaryotic cells**?
- **smaller (0.5 - 5 micrometers in diameter) than eukaryotic cells (10-100 micrometers in diameter)** - don't contain membrane bound organelles - cytoskeleton is much less developed - cell wall made of **peptidoglycan** - have**smaller ribosomes (70s compared to 80s)** - no nucleus: DNA floats in cytoplasm as a loop, not wound around histone proteins
65
What are the subcellular structures exclusive to prokaryotic cells?
- flagella - plasmid - pili - protective slime capsule
66
What is the function of **flagella**?
*Rotates to move the cell*
67
What is the function of **plasmids**?
*Small loop of DNA*
68
What is the function of **pili**?
*Allows adherence of cells*
69
70
What is the function of **protective slime/waxy capsule**?
*Protects cell from physical and chemical attacks*
71
How do prokaryotic cells divide?
Through **binary fission**

A Level Biology OCR A (7 decks)

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