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Biology A Level > Cell Structure > Flashcards

Cell Structure Flashcards

1
Q

Give 10 parts of a basic animal cell

A

Nucleus
Nucleolus
Nuclear pore
Mitochondrion
Cytoplasm
Ribosomes
Cell surface membrane
Golgi body/Golgi Apparatus
Rough endoplasmic reticulum
Smooth endoplasmic reticulum

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2
Q

Outline how to make a temporary mount of plant tissue to observe starch grains using an optical microscope

A
  1. Add a drop of water to a glass slide,
  2. Obtain a thin section of plant tissue to place on the slide on the water,
  3. Stain the starch grains blue-black by adding iodine (potassium iodide) solution
  4. Using a mounted needle, lower the cover slip down onto the sample, avoiding trapping any air bubbles
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3
Q

What’s the formula for magnification

A

Magnification=image size/actual size

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4
Q

What’s the definition of resolution

A

The minimum distance between two objects, where they can still be seen as two separate objects. The smaller this distance, the higher the resolution

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5
Q

What is magnification

A

Making an objects appearance increase in size

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6
Q

What type of microscope obtains a higher resolution

A

The electron microscope

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7
Q

Why do light microscopes obtain a lower resolution image than an electron microscope

A

Because there are longer wavelengths between light than between electrons.

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8
Q

Give 4 pros and 2 cons of the optical microscope

A

Con- lower resolution due to longer wavelength
Con- can only view the nucleus, cytoplasm and cell walls

Pro- can view live specimens
Pro- can show colour
Pro- a student can do (not as complex)
Pro- cheaper

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9
Q

Give 2 pros and 6 cons of the electron microscope

A

Pro- 2000x greater resolution due to shorter wavelength
Pro- can be used to view smaller organelles such as mitochondrion, ribosomes, endoplasmic reticulum, lysosomes and cell surface membranes

Con- more expensive
Con- can only view dead specimens (because the interior of the microscope must be a vacuum)
Con- can only view very thin specimens
Con- no colour
Con- requires a more time-consuming, complex preparation,
Con- the production of artefacts ( fake images created by the staining process of the specimen )- hard to distinguish between these and cell organelles

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10
Q

What are the two types of electron microscope

A

Scanning Electron microscope (SEM)

Transmission Electron Microscope (TEM)

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11
Q

How do Scanning Electron Microscopes work ?
Does this require the object to be thinly sliced?

A

Electrons are deflected off the surface of the object, creating a 3D image of the surface of the object. This doesn’t require the object to be thinly sliced.

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12
Q

How do Transmission Electron Microscopes work?
Does this require the object to be thinly sliced

A

Electrons are transmitted (pass through) the object, creating a 2D image including internal structures. This requires the object to be thinly sliced.

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13
Q

Which type of electron microscope has a higher (better) resolution

A

The Transmission Electron Microscope

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14
Q

Outline the organisation of cells

A

Cells are organised into tissues, tissues are organised into organs, organs are organised into organ systems, organ systems are organised into organisms

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15
Q

Outline the organisation of cells

A

Cells are organised into tissues, tissues are organised into organs, organs are organised into organ systems, organ systems are organised into organisms.

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16
Q

Outline the structure (3) and function (1) of a cell-surface membrane

A

Structure:
-Made of a phospholipid bilayer and proteins
-Some adapted cells have a folded cell membrane (this folding is called microvilli and increases the surface area)
- Has proteins embedded in a mosaic pattern which have specific functions

Function: to control what substances enter and exit the cell

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17
Q

Outline the structure and function of a cell-surface membrane

A

Structure:
-This is the outermost membrane surrounding the outside of the cell.
-Made of a phospholipid bilayer and proteins
-Some adapted cells have a folded cell membrane (this folding is called microvilli and increases the surface area)

Function: to control what substances enter and exit the cell

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18
Q

Outline the function and structure of the nucleus

A

Function: to store genetic information (DNA) to produce proteins. Since most enzymes are protein, this is how it controls the activities of the cell.

Structure:
- Contains chromosomes, consisting of protein (histone) bound, linear DNA, and one or more nucleoli (this is the singular term for nucleolus)
-Has a nuclear envelope around the outside which is a double membrane
- there are nuclear pores throughout the envelope, allowing mRNA to exit the nucleus
-The chromosomes are made from chromatin (DNA wrapped around histones), containing the code for protein synthesis.
- The nucleolus is where rRNA and ribosomes are synthesized

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19
Q

What is the function of the nucleolus

A

The production of ribosomal RNA (rRNA) and ribosomes

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20
Q

What is the function (1) and structure (5) of mitochondria

A

Function: Site of aerobic respiration. They synthesise ATP (the form of energy used by all cells for reactions such as active transport, protein synthesis, movement of vesicles etc)

Structure:
- Has a double membrane (outer and inner)
-Inner membrane is folded into cristae. This is where the enzyme ATPsynthase is embedded.
-Contains fluid-filled region called the matrix
- Contains it’s own, circular DNA,
-Contains it’s own 70s ribosomes

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21
Q

Where does anaerobic respiration take place

A

In the cytoplasm

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22
Q

What is ATP and describe it

A

Adenosine Triphosphate - a nucleotide derivative made from a molecule of ribose, the base adenine and three phosphate groups.
-It’s the form of energy used by all cells for reactions such as active transport, protein synthesis, the movement of vesicles etc,

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23
Q

What is formed from the hydrolysis of ATP

A

Adenosine diphosphate (ADP) and an inorganic phosphate (Pi)

24
Q

What does the enzyme ATP hydrolyse catalyse

A

The hydrolysis of ATP into ADP and Pi

25
What can the inorganic phosphate (Pi) released during ATP hydrolysis be used for
To phosphorylate other compounds, often making them more reactive
26
How is ATP re-synthesised and what catalyses this
Phosphorylation It's re-synthesised by the condensation of ADP and Pi, catalysed by the enzyme ATP Synthase (during respiration and photosynthesis)
27
Outline the function (1) and structure of chloroplasts (6)
Function: the site of photosynthesis in plants and algae Structure: -Has a double outer membrane -Contains its own, circular DNA -Contains its own, smaller (70s) ribosomes -has a fluid filled region called the stroma -contains starch grains to store alpha glucose, -Made up from stacks of thylakoid membranes called grana that contain the chlorophyll pigments
28
Outline the function (5) and structure of the golgi apparatus/body
Structure - the golgi apparatus is made up of flattened layers of membrane bound sacs called cisternae and associated vesicles (golgi vesicles) Function: -Receives substances from the endoplasmic reticulum, processes them and then distributes them to their destination -Modifies and processes triglycerides by combining them with proteins, then packages them for release from the cell via exocytosis. - Forms glycoproteins by Joining sugars to polypeptides - Forms vesicles to secrete proteins/glycoproteins out of the cell via the surface membrane, -Forms Lysosomes
29
Outline the structure and function of lysosomes
Function - -to release hydrolytic (digestive) enzymes when they fuse with a vesicle/phagosome -to remove dead or worn-out organelles Structure - these are a small, round membrane-bound organelle containing digestive enzymes. They have transport proteins on the membrane surface.
30
Outline the function and structure of ribosomes
Function - the site of translation and part of protein synthesis Structure - made from ribosomal RNA (rRNA) and proteins in the nucleolus, forming two subunits (a larger and a smaller subunit(
31
Outline the structure and function of the rough endoplasmic reticulum
Structure - flattened sacs of membrane stacked together with ribosomes attached Function - the site of protein synthesis (specifically any membrane proteins or proteins to be secreted out of the cell) and transport of the protein
32
Outline the structure and function of the smooth endoplasmic reticulum
Structure - made up of flattened, membrane bound sacs stacked together and tubules called cisternae. Function - to synthesise lipids, -detoxification of toxins - transportation of other substances such as proteins and carbohydrates.
33
Outline the structure and function of the cell wall
Structure: -in plants and algae, the cell wall will be made from cellulose -in fungi, the cell wall will be made from chitin - in bacteria, the cell wall will be made from Peptidoglycan Function - to give structural support to the cells, preventing it from changing shape
34
Outline the structure and function of the cell wall
Structure: -in plants and algae, the cell wall will be made from cellulose -in fungi, the cell wall will be made from chitin - in bacteria, the cell wall will be made from peptidoglycan Function - to give structural support to the cells, preventing it from changing shape
35
Outline the function of the cell vacuole
It is used to store cell sap and to maintain structural support of the plant cell
36
Give 4 things all prokaryotic cells have that eukaryotic cells don't have
-has a cytoplasm that lacks membrane - bound organelles, -only 70s ribosomes -no nucleus; instead they have a singular circular DNA strand that is free in the cytoplasm (and isn't associated with proteins) -a cell wall that contains peptidoglycan
37
Give 3 things that only some prokaryotic cells have
-one or more plasmids -a capsule surrounding the cell -one or more flagella
38
Outline the structure of viruses
-has ginetic material (either DNA or RNA) -Has a capsid (protein shell) -has attachment proteins -some viruses such as HIV particles also contain an enzyme called reverse transcriptase, if they have an RNA genome -some have a lipid bilayer (which they have stolen from the host cell)
39
What are the names of the two processes needed to separate cell components/organelles
Cell fractionation Ultracentrifugation
40
Outline cell fractionation
1. Homogenise (blend) to break open the cells 2. Filter to remove the large cell debris 3. Suspend in an ice-cold isotonic buffer solution
41
Why is the buffer solution used in cell fractionation ice cold
Because it slows enzyme activity to prevent the breaking down of the organelles
42
Why is the buffer solution used in cell fractionation isonic
Because it has the same water potential as the organelles to prevent osmosis, so there will be no osmotic lysis of organelles and no shrinkage.
43
Why is a buffer used in cell fractionation
To maintain the pH so that any proteins aren't denatured
44
Outline ultracentrifugation
1. Centrifuge (spin the organelles) on a slow speed, 2. The first pellet (the solid that collects at the bottom) will contain all the nuclei as it is the densest organelle 3. Remove the supernatant (the fluid part) from above the pellet. 4. Centrifuge the supernatant as a faster speed 5. Mitochondria and chloroplasts will be found in the second pellet, as they are less dense. 6. Repeat if required
45
Outline how plant and animal cells get energy
Plant and animal cells release energy from glucose - this process is called respiration. However, a cell can't get it's energy directly from glucose. So, in respiration, the energy released from glucose is used in the Mitochondria to make ATP. Once made, ATP diffuses to the part of the cell that needs energy. The energy is stored in the high energy bonds between the phosphate groups, and is released via hydrolysis reactions.
46
Give one example of a nucleotide derivative, and why this is a nucleotide derivative.
ATP. This is a nucleotide derivative because it's a modified form of a nucleotide.
47
Outline how ATP is used for energy
Used- when energy is needed by a cell, ATP is broken down into ADP and Pi. This is a hydrolysis reaction. A phosphate bond is broken and energy is released. This reaction is catalysed by the enzyme ATP hydrolase. ATP hydrolysis can be coupled to other energy required reactions in the cell, meaning the extra energy released can be used to make the other reaction happen rather than being lost as heat.
48
What do ADP and Pi stand for
ADP= adenosine diphosphate Pi= inorganic phosphate
49
What do ADP and Pi stand for
ADP= adenosine diphosphate Pi= inorganic phosphate
50
What is a polymer of nucleotides called
A Polynucleotide
51
Explain how nucleotides are joined together to make a Polynucleotide
The nucleotides join up via a condensation reaction between the phosphate group of one nucleotide and the sugar of another This forms a phosphodiester bond (consisting of the phosphate group and two ester bonds) The chain of sugars and phosphates is known as the sugar-phosphate backbone. This forms a Polynucleotide.
52
What is the limit of resolution for a standard light microscope and why
The limit of resolution for a standard light microscope is around 200nm, because the wavelength of visible light is quite high meaning any distance smaller than this can't be distinguished by the human eye
53
Give the key features of eukaryotic cells
1) having DNA in a membrane bound nucleus 2) their DNA is tightly wrapped around proteins called histones, to form chromosomes 3) their DNA is a linear molecule (as the ends of the DNA molecule in a chromosome aren't joined together to form a loop) 4) they contain membrane bound organelles
54
What is the cell wall made of in plant cells and fungal cells and bacteria cells
Plant cells - cellulose Fungal cells - chitin Bacterial cells- Peptidoglycan
55
Draw a basic animal cell, labeling the basic organelle

Biology A Level (15 decks)

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