A2.2 Cell Structure

Question 1

Cell Theory

Answer 1

1. All living things are made of cells.
2. Cells are the smallest units of life
3. All cells come from pre existing cells

Question 2

Exceptions to Cell Theory

Answer 2

1. Skeletal Muscle: Multinucleated Cells
2. Giant Algae: Expected to be multicellular bc up to 100mm in length but is unicellular
3. Aseptic Fungi: Hyphae is multinucleated
4. Phloem: Sieve tube element and companion cell -> Has no nucleus and minimal cellular content
5. Red blood cell: Biconcave and has no nucleus

Question 3

Resolution

Answer 3

Shortest distance between two seperate points in a microscope’s field of view that can still be distinguished as seperate objects

Question 4

Magnification

Answer 4

The size of an image compared to the actual size of the object

Question 5

Freeze Fracture Microscopy

Answer 5

Freezing and breaking a sample to see internal structure

Question 6

Cryogenic Electron Microscopy

Answer 6

Freezing sample to improve resolution and reduce damage under electron microscopy

Question 7

Immunofluorescence

Answer 7

Visualise certain structures using fluorophore that attaches to antibodies specific for antigens on a structure

Question 8

Fluorescent dyes

Answer 8

Brightly coloured spots to be seen in light microscopy

Question 9

Lysis

Answer 9

When plasma membrane bursts from excess pressure or viruses

Question 10

Autolysis

Answer 10

Lysis caused by the cell itself

Question 11

3 Structures in a typical cel

Answer 11

1. Plasma Membrane
2. Cytoplasm
3. DNA

Question 12

Plasma Membrane

Answer 12

Substance made up of proteins and lipids which create the outer boundary of the cell that encloses all its contents and controls entry and exit of substances. It can pump them in even when the concentration outside is low.

Question 13

Cytoplasm

Answer 13

Jelly like substance that contains a lot of H2O to dissolve a lot of organic compounds and ions. It contains enzymes to catalyse reactions for metabolism to provide the cell with energy and produce substances that make up the cell.

Question 14

DNA

Answer 14

Contains information needed for a cell to carry out all functions and instructions for making protein. It can be copied and passed onto daughter cells.

Question 15

Prokaryotic cells

Answer 15

• Do not contain membrane bound organelles
• No compartmentalisation
• Can only divide by binary fission
• No nucleus

Question 16

Eukaryotic cells

Answer 16

• Internal Compartmentalisation
• Mitosis and Meiosis
• Contains a nuclei

Question 17

70s ribosome

Answer 17

• Made up of ribosomal RNA and proteins
• Consists of 2 sub-units -> Large and small
• Used for protein synthesis

Question 18

Nucleoid Region (In Prokaryotes)

Answer 18

• Naked Circular DNA
• Not associated with histone proteins
• Contains genetic material to control all modification

Question 19

Plasmid DNA

Answer 19

• Consists of circular DNA
• Doesn’t contain genes that are essential for survival

Question 20

Prokaryotic Cell Wall

Answer 20

• Made up of peptidoglycen
• Used to prevent the excessive uptake of H2O

Question 21

Flagella

Answer 21

• Cork screw shaped structure
• Used for locomotion

Question 22

Mesosome

Answer 22

• Infolding on the plasma membrane where respiration takes place
• Not classified as an organelle

Question 23

Slime Capsule

Answer 23

• Used to protect the bacteria from being recognised by host

Question 24

Pili

Answer 24

• Hair like structure
• Allows the bacteria to attach to the host cell
• Allows exchange of genetic material between the bacteria through conjugation

Question 25

Mitochondria

Answer 25

- Double membrane structure - Possess their own circular DNA and 70s ribosome - Where aerobic respiration takes place to create ATP to drive cellular processes

Question 26

Nucleolus

Answer 26

Where ribosomes are being made

Question 27

Microvilli

Answer 27

- Increase surface area for absorbtion

Question 28

Free floating 80s ribosome

Answer 28

- Made up of rRNA and protein - Produce proteins that would be used within the cell

Question 29

Lysosome

Answer 29

- Type of vesicle that contains hydrolytic enzymes for intracellular digestion to break down substances

Question 30

Nuclear Pores

Answer 30

- Allows the exchange of materials between the nucleus and surroundings

Question 31

Cytoskeleton

Answer 31

- Used to maintain cell shape and keep organelles in place

Question 32

Transport Vesicle

Answer 32

- Transport the protein being produced by RER to Golgi

Question 33

Rough Endoplasmic Reticulum (RER)

Answer 33

- Synthesise and package the proteins for secretion to lysosome

Question 34

Golgi Apparatus

Answer 34

- Modify and package proteins and lipids by adding carbohydrates - Modified substance will be packaged into a vesicle for secretion

Question 35

Chromatin

Answer 35

- Condensed Chromosome which consists of linear DNA Molecules associated with histone proteins

Question 36

Secretary Vesicle

Answer 36

- Transports the molecules to plasma membrane for secretion

Question 37

Smooth Endoplasmic Reticulum

Answer 37

- Synthesise lipids - Store calcium ions - Detoxification

Question 38

Centriole

Answer 38

- Type of centrosome - Used to organise the microtubles during nuclear divisions

Question 39

Large Central Vacuole

Answer 39

- Type of vesicle - Stores H2O and minerals to maintain turgeon pressure

Question 40

Cell Wall

Answer 40

- Made up of cellulose - Prevent excessive uptake of H2O

Question 41

Plasmodesmata

Answer 41

- Allows for the lateral movement of substance in between plant cells such as sucrose

Question 42

Chloroplast

Answer 42

- Double membrane structure that contains its own circular DNA and 70s ribosomes - Contains photosynthetic pigments which can absorb light for photosynthesis to convert light into chemical energy