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(A Level) Biology > Topic 3 (3.1 - 3.5 + 3.10) - Prokaryotes + Eukaryotes + Mitosis > Flashcards

Topic 3 (3.1 - 3.5 + 3.10) - Prokaryotes + Eukaryotes + Mitosis Flashcards

1
Q

What is a eukaryotic cell

A

A cell that contains both a nucleus and membrane bound organelles

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2
Q

What is the range in size of eukaryotic cells

A

Most are between 1 - 100 micrometers

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3
Q

What is the cell surface / plasma membrane

A

A partially permeable selective barrier that is made of a phospholipid bilayer

Its found in ALL CELLS

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4
Q

What is the structure of the nucleus

A

It contains 2 membranes called the nuclear envelope (double membrane bound organelle

It has nuclear pores - allows the mRNA to leave

Nucleolus - Densely packed area of chromatin. rRNA (ribosomal RNA) is made here

Nucleoplasm - empty space in the nucleous

Chromatin - Double stranded + codes for proteins.
Strands of linear DNA are wrapped around histone proteins

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5
Q

What is the nucleus

A

A double membrane bound organelle, that holds the genetic material of a eukaryotic cell

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6
Q

What is the rough endoplasmic reticulum

A

An interconnected, single-membrane bound organelle
It is made of several sheets and tubes (cisternae), which connect it to the nucleus

Ribosomes are attached to it ( which is why its rough)

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7
Q

What does the rough endoplasmic reticulum do

A

It folds and processes proteins made at the ribosomes

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8
Q

Describe the structure of the rough endoplasmic reticulum

A

It is a single membrane with ribsomes attached.

It has a central lumen

It has cisternae

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9
Q

What are cisternae

A

They are flattened membrane vessicles

Ciaternae can be found in the Endoplasmic reticulum and the golgi apparatus

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10
Q

What is the smooth endoplasmic reticulum

A

A space which synthesises and processes, lipids and steroids

(e,g hormones)

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11
Q

Why is the smooth endoplasmic reticulum called smooth

A

As it has no ribosomes attached to it

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12
Q

What is the golgi apparatus

A

A single membrane-bound organelle made of several cisternae

It modifies and processes proteins (by adding carbohydrates)
It concentrates molecules (removes water)
It activates enzymes

It can also transport / package proteins and lipids in secretory vesicles

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13
Q

What does the golgi apparatus look like (how should it be drawn)

A

It is made up of at least 3 curved cisterna and is surrounded by vessicles

The cisternae get larger in size moving towards the trans face

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14
Q

What is the cis face of the golgi apparatus

A

the side that faces the rough endoplasmic reticulum
(receives transport vesicles)

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15
Q

What is the trans of the golgi appparatus

A

the side that faces the plasma membrane
(Releases secretory vessicles)

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16
Q

What are mitochondria

A

A double membrane bound organelle that is site of aerbic respiration in a cell

It is responsible for the production of ATP

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17
Q

What is the structure of a mitochondria

A

It has an outer membrane and an inner membane, with intermembranal space between the two

The inner membrane is folded into cristae

It contains ribosomes

It has a matrix (similar to the cytoplasm) - contains the ribosomes, proteins and enzymes

Mitochondial DNA

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18
Q

What is the structure of mitochondrial DNA

A

A circular loop of DNA
It doesnt contain Histone proteins
It has fewer genes
As it is a loop there are no exposed phosphate groups

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19
Q

What are ribosomes

A

Organelles that are the site of protein synthesis

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20
Q

What is the cristae

A

The folded inner membrane of a mitochondria

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21
Q

What are the size of eukaryotic ribosomes

A

80s

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22
Q

What are lysosomes

A

Single membrane sacs that contain hydrolytic (digestive) enzymes

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23
Q

What is apoptosis

A

Programmed cell death

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24
Q

Are lysosomes larger or smaller than most vesicles

A

Larger

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25
What are centrioles (centrosome)
Microtubular structures that are found at right angles to each other Each cell has a pair of centrioles
26
What is the purpose of centrioles
Forming spindle fibers during mitosis
27
Do centrioles have a membrane
No
28
What two ways can centrioles appear under a microscope
Two dark rectangular structures perpendicular to each other A circular shape created by a repeated unit of 3 tibes connected tohether
29
30
What is a prokaryotic cell
A cell which contains no nucleus or no membrane bound organelles
31
What is the typical size of a prokaryote
0.5 - 5 micrometers
32
What organelles do MOST Eukaryotes always contain
Plasma membrane Golgi apparatus Mitochondria Rough endoplasmic reticulum Smooth endoplasmic reticulum Lysosomes Centrioles Ribosomes Nucleus
33
What are plasmids
Small loops of DNA (few genes) that contain accessory genes
34
What is a mesosome
Inward folds of the plasma membrane Site of respiration
35
What are pilli
Short hair like structures They stick to surfaces and transfer genetic material between cells (plasmids)
36
What is conjugation (prokaryotic cells)
The horizontal transfer of genetic material
37
What is a flagellum
A thread like structure that rotates to move a cell in liquids (propulsion)
38
What is the slime capsule
A secreted slime layer that protects prokaryotes from the imune system and prevents dehydration of the cell
39
What is the cell wall like in prokaryotes
It supports structure and shape It is made of either Murein or Peptidoglycan
40
What are the size of ribosomes in prokaryotes
70s
41
What structres are always found in prokaryotes
Ribosomes Cell wall Plasma cell membrane Circular DNA / nucleoid
42
How is DNA found in prokaryotes
It is circullar DNA found in an area called the nucleiod It is fouund free floating in the cytoplasm It has no histone proteins
43
What does the golgi apparatus do
- It processes and modifies proteins (adds carbohydrates) / lipids - It concentrates proteins (removes water) - It activates enzymes - It packages enzymes ito vesicles -It trims proteins (makes them smaller)
44
Are prokaryotes or eukaryotes always unicellular
Prokaryotes are always unicellular
45
How do you find image size using actual size and magnification
Image = actual x magnification
46
How do you calibrate an eyepiece graticule
Place the stage micrometer on the micrometer stage Line up the divisions on the eyepiece graticule with those of the micrometer Work out the length of one eyepiece graticule unit in micrometers (Repeat for each magnification)
47
How do you measure the length of an object using an eyepiece graticule
Place a slide on the microscope slide Measure the specimens length in eyepiece graticule lengths. Multiply the length of one eyepiece graticule by the number the spwcimen is
48
Why can the same organelle look different under a microscope
They can be viewed at different angles, so their cross section is cut differently by the microscope. This causes their shape to appear different
49
How do you calculate the length of 1 eyepiece graticule division
Find a pint to compare the eyepiece practice and micrometer Multiply the number of stage micrometer divisions by the length of 1 division Divide this value by the amount of eyepiece divisions (and convert to micrometers if necessary)
50
How do you convert milimeters to micrometers
Multiply by 100
51
How are proteins transported around a cell
1) They are translated in the ribosomes and enter the RER if they require modification The 3D protein is then packaged into transport vesicles 2) The vesicles fuse with the cisternae on the cis face of the golgi After going through a process they are packaged into secretory vesicles which 'pinch off' 3) Exocytosis Vesicles move to the plasma membrane and fuse to it The protein is then secreted
52
Are all proteins secreted out of a cell
No some proteins remain in vesicles inside of the cell. E.g lysosomes and channel / carrier proteins
53
What is the cell cycle
The steps a somatic cell goes through to grow and divide into two daughter cells
54
What happens in interphase
The cells size, mass and DNA increases
55
What happens in mitosis
Nuclear division, producing two nuclei
56
Why does mitosis occur
For growth Repairing damaged tissues / replacing dead cells Asexual reproduction
57
What are the three stages of interphase
G1 - growth phase 1 S - synthesis phase G2 - growth phase 2
58
What occurs in G1
The cell grows (increase in cytoplasm and cell membrane) Organelles duplicate
59
Other than to ensure the cells are identical, why would more mitochondria be produced in g1
Both interphase and mitosis occur a lot of energy Having more mitochondria means more ATP can be produced
60
What occurs in S phase
DNA is replicated (from 2n to 4n) Centrioles will double
61
Why is DNA replicated before mitosis occurs
To ensure there is enough DNA for the cell to divide and be genetically identical to the original cell
62
What happens in G2
The cell continues to grow The cell is 'checked' to ensure there is enough dna / organelles for mitosis
63
What are the stages of mitosis
Prophase Metaphase Anaphase Telophase
64
What are the 3 stages in the cell cycle
Interphase Mitosis Cytokenisis
65
What happens in prophase
DNA condenses into chromosomes Nuclear envelope and nucleolus disappear Centrioles migrate to opposite poles and centrioles begin to form
66
What happens in metaphase
Chromosomes align at the equator of the cell (above each other) Spindle fibers attach to the centromeres of the chromatids
67
What happens in anaphase
Spindle fibers contract and shorten splitting the centromere Chromatids are pulled apart to opposite poles
68
What happens in telophase
The nuclear envelopes reform around the DNA Nuclei reform Spindle fibers break down Chromosomes decondense The cell begins to pinch
69
What happens in cytokenisis
The plasma membrane constricts around the center of the cell A contractile ring forms and contracts to aid splitting (creating a cleavage furrow) The cell splits producing two genetically identical diploid daughter cells
70
How do you calculate a mitotic index
(Number of cells in mitosis ÷ total number of cells) × 100

(A Level) Biology (13 decks)

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