Cells

Question 1

Nucleus

Answer 1

Site of DNA replication + transcription (mRNA is made) and contain genetic code for each cell.

Question 2

Nucleus Structure

Answer 2

Nuclear Envelope
Nuclear pores
Nucleoplasm
Chromosomes - protein bound linear DNA
Nucleolus- small, sphere site of RNA production to produce ribosomes

Question 3

RER Function + Structure

Answer 3

System of membrane bound flattened sacs, surface covered with ribosomes.

Proteins enter and are folded and processed then transported to Golgi apparatus in vesicles.

Question 4

SER structure + function

Answer 4

System of membrane bound flattened sacs but no ribosomes.

Synthesised lipids and carbs and also store it.

Question 5

Golgi Apparatus

Answer 5

Add carb to proteins to form glycoprotein. Transfer/modify/store lipids.

Finished products transported back to cell surf in Golgi vesicle where they fuse with the membrane and contents released.

Question 6

Lysosome

Answer 6

Filled with digestive enzymes
Hydrolyse bacteria/virus to completely break down dead cells (autolysis), and (exocytosis) where products are released outside after it’s destroyed, digest worn out components.

Question 7

Mitochondria

Answer 7

Double membrane that form cristernae, mitochondrial matrix and loop of DNA.

Site of aerobic respiration

Question 8

Ribosomes

Answer 8

Site of protein synthesis, found in prokaryotic and eukaryotic, not membrane bound. Made up of RNA and proteins.
80’s and 70’s

Question 9

Vacuoles

Answer 9

Found in plant cells, makes it turgid (provide strength, temp store of sugars and amino acid and contain pigment colouring petals (attract pollinators)

Fluid filled surrounded by single membrane, tonoplast.

Question 10

Chloroplast

Answer 10

Surrounded by thylakoid (stack up to create grana), embedded with proteins and pigment e.g chlorophyll, stroma (fluid surrounding thylakoid) with lots of enzymes.

Question 11

Cell Wall

Answer 11

Plants- cellulose
Fungi- chitin

Question 12

Plasma Membrane

Answer 12

Controls exit and entrance of molecules
Made up of phospholipid bilayer

Question 13

What are the key features of prokaryotic cells?

Answer 13

Prokaryotic cells have a capsule, ribosomes, DNA in a single circular loop, plasmids, a cell wall made of murein, flagella, and membrane infoldings (mesosomes).

Question 14

What is the function of the capsule in prokaryotic cells?

Answer 14

The capsule prevents desiccation and protects the cell from antibiotics and viruses.

Question 15

How do ribosomes in prokaryotic cells differ from those in eukaryotic cells?

Answer 15

Prokaryotic ribosomes are smaller (70s) compared to eukaryotic ribosomes (80s).

Question 16

What is a plasmid?

Answer 16

A plasmid is a small loop of DNA that can be shared between cells and usually contains useful genes, such as antibiotic resistance.

Question 17

What is the composition of the cell wall in prokaryotic cells?

Answer 17

The cell wall is made of murein, which is a mix of polysaccharides and peptides.

Question 18

What is the role of the flagellum in prokaryotic cells?

Answer 18

The flagellum is used for locomotion.

Question 19

What is the function of membrane infoldings (mesosomes) in prokaryotic cells?

Answer 19

Mesosomes increase the surface area for respiration or photosynthesis.

Question 20

What are the steps of binary fission in prokaryotes?

Answer 20

1. DNA and plasmids replicate. 2. Cell elongates and DNA moves to opposite poles. 3. Cytoplasm begins to divide and new cell walls form. 4. Cytoplasm divides to produce two daughter cells.

Question 21

What are the characteristics of fungi?

Answer 21

Fungi are eukaryotic, similar to plant cells, but contain no chloroplasts and have cell walls made of chitin.

Question 22

How do viruses differ from prokaryotic and eukaryotic cells?

Answer 22

Viruses are acellular non-living particles and are 1000x smaller than bacteria.

Question 23

What is the structure of a virus?

Answer 23

Viruses consist of genetic material (RNA) protected by a protein coat called the capsid, and may also have a lipid envelope.

Question 24

What is the process of virus replication?

Answer 24

1. Virus detects host cell by recognizing protein markers. 2. Virus injects genetic material into the cell. 3. Cell reproduces genetic material and creates new viral proteins. 4. Virus leaves the cell using some of its membrane.

Question 25

What is the surface area to volume ratio in single-celled organisms?

Answer 25

Single-celled organisms have a very large surface area to volume ratio.

Question 26

What is the surface area to volume ratio in multi-cellular organisms?

Answer 26

Larger multi-cellular organisms have a smaller surface area to volume ratio.

Question 27

What is the consequence of a smaller surface area to volume ratio in multi-cellular organisms?

Answer 27

This results in a larger distance from the middle to the outside.

Question 28

What is a characteristic of larger multi-cellular organisms regarding metabolic rates?

Answer 28

They also have higher metabolic rates, which demands efficient transport of waste out of the cells and reactants into the cells.

Question 29

What is an example of a structure that aids absorption in multi-cellular organisms?

Answer 29

Villi and microvilli aid in the absorption of digested food. ## Footnote Example: Villi + microvilli - absorption of digested food.

Question 30

What is an example of a structure that facilitates gas exchange?

Answer 30

Alveoli and bronchioles facilitate gas exchange. ## Footnote Example: Alveoli + bronchioles - gas exchange.

Question 31

What is an example of a structure involved in gas exchange during respiration?

Answer 31

The trachea is involved in gas exchange. ## Footnote Example: Trachea - gas exchange.

Question 32

Type Of Microscopes

Answer 32

Optical (Light) Electron Microscope - TEM, SEM

Question 33

Magnification

Answer 33

How many times larger the image is compared to the object.

Question 34

Resolution

Answer 34

Minimum distance between 2 objects, in which they can still be viewed as separate.

Question 35

Optical Microscope

Answer 35

Determined via WL of of light Beam of light is condensed by using a lense to create an image. Poorer resolution, lower mag, can have coloured image and view living samples.

Question 36

Electron Microscopes

Answer 36

Determined by WL of beam of electron that is condensed by electromagnets to create an image. Higher resolving and magnification power, B+W images (colour can be added), sample must be in a vacuum ( electrons can easily be absorbed), only view non living.

Question 37

TEM

Answer 37

View extremely thin specimens, stained and placed in a vacuum. Electron gun produces a be of electrons that transmit through the specimen, some part absorb others don’t. You get a 2D image of the internal structure.

Question 38

SEM

Answer 38

Created 3D image of external sample as specimens does not need to be thin due to electrons not passing through instead beamed on its surface and electrons scattered in different ways.

Question 39

Magnification Calc

Answer 39

M= I/A

Question 40

Eye piece Graticule

Answer 40

A scale inside the optical Microscope, used to measure size of object viewing under it.

Question 41

Stage Micrometre

Answer 41

2nd scale, to measure eyepiece graticule

Question 42

Stages to measure size of specimen

Answer 42

1) Line up stage micrometer and eye piece graticule while looking through eyepiece. 2) Count how many divisions on eye piece graticule fit into 1 division of stage micrometer 3) Work out in up 4) now graticule is calibrated you can measure size of cell by length x UP

Question 43

Cell Fractionation

Answer 43

Used to isolate the different organelle component for function to be studied

Question 44

Condition to be kept in

Answer 44

Cold - reduce enzyme activity as when you break open cell you’ll be releasing enzymes which can damage organelles Isotonic -Don’t have excess h20 moving in + out by osmosis can lead to shrink/burst Buffered- if too acid/alkaline can damage organelle

Question 45

Steps for cell fractionation

Answer 45

Step 1) Homogenisation - breaks open cell e.g using blender Step 2) Filteration - to remove large cell debris Step 3) ultracentrifugation - put sample in centrifuge and spin and different speeds to separate organelle depending on their density.