B3 Cell Structure

Question 1

What are the two domains into which all organisms are divided?

Answer 1

Eukaryotes and prokaryotes.

Question 2

What distinguishes eukaryotic cells from prokaryotic cells?

Answer 2

Eukaryotic cells contain a nucleus and other membrane-bound organelles, while prokaryotic cells do not.

Question 3

What is the function of the nucleus?

Answer 3

Contains DNA, controlling cell activities by containing instructions to make proteins.

Question 4

What is chromatin?

Answer 4

DNA associated with histone proteins.

Question 5

What is the function of the nucleolus?

Answer 5

Ribosome production.

Question 6

What is the nuclear envelope?

Answer 6

A double membrane surrounding the nucleus with pores.

Question 7

What is the role of RER?

Answer 7

Folds and processes proteins synthesised in the ribosomes and transport to Golgi apparatus via vesicle

Question 8

What is synthesized in the smooth endoplasmic reticulum (SER)?

Answer 8

Lipids, including cholesterol and steroid hormones.

Question 9

What is the function of the Golgi apparatus?

Answer 9

Modifies and repackages proteins and lipids into vesicles; site of lysosome synthesis.

Question 10

What is the function of ribosomes?

Answer 10

Translation of RNA into protein (protein synthesis).

Question 11

What is the function of mitochondria?

Answer 11

ATP is released during aerobic respiration.

Question 12

What are cristae?

Answer 12

Folds in the inner membrane of mitochondria.

Question 13

What is the function of lysosomes?

Answer 13

Contain digestive enzymes to destroy old organelles or foreign material which are engulfed by the lysosome

Question 14

What is the function of chloroplasts?

Answer 14

The site of photosynthesis.

Question 15

What is the plasma membrane made of in eukaryotic cells?

Answer 15

A phospholipid bilayer with proteins and cholesterol.

Question 16

What is the function of the plasma membrane?

Answer 16

Controls the movement of substances into and out of the cell.

Question 17

What is the role of centrioles?

Answer 17

Formation of spindle fibers during mitosis and formation of cilia and flagella.

Question 18

What is the function of the cell wall?

Answer 18

Provides support to the cell.

Question 19

What is the cell wall made of in plants, fungi and prokaryotes?

Answer 19

Cellulose, chitin, and murein, respectively.

Question 20

What is the function of flagella?

Answer 20

Propel the cell forward.

Question 21

What is the function of cilia?

Answer 21

Sweep mucus up the windpipe (in epithelial cells lining the trachea).

Question 22

What is the function of a vacuole?

Answer 22

Stores cell sap, nutrients, and proteins; helps keep plant cells turgid and rigid by maintaining the cells pressure

Question 23

What are plasmodesmata?

Answer 23

Channels between plant cells that enable communication.

Question 24

What is a tissue?

Answer 24

A group of specialised cells working together to perform a function

Question 25

What is an organ?

Answer 25

A collection of tissues performing a specific function.

Question 26

What is an organ system?

Answer 26

Multiple organs connected together.

Question 27

What type of tissue forms capillary walls?

Answer 27

Endothelium.

Question 28

Name three differences between eukaryotic and prokaryotic cells.

Answer 28

Eukaryotes have membrane organelles, prokaryotes lack membrane-bound organelles Eukaryotes have linear DNA whilst prokaryotes have circular DNA Prokaryotes have smaller ribosomes (70S).

Question 29

What are plasmids?

Answer 29

Small circular rings of DNA in prokaryotes.

Question 30

What is murein?

Answer 30

A type of glycoprotein that makes up bacterial cell walls.

Question 31

What is the slime capsule in bacteria?

Answer 31

A capsule that protects bacteria against an immune system attack.

Question 32

How do bacteria replicate?

Answer 32

Binary fission.

Question 33

What is the function of the viral capsid?

Answer 33

A protein coat surrounding the nucleic acid (DNA or RNA) and enzymes.

Question 34

How do viruses infect host cells?

Answer 34

Viruses use their attachment proteins to bind to complementary receptor proteins on the surface of host cells They then inject their genetic material/ nucleic acids into the host cell Then host cells ribosomes will replicate the viral particles as the host cells machinery is hijacked

Question 35

How do prokaryotic cells replicate via binary fission

Answer 35

Circular DNA replicate ( plasmids can replicate as many times as they want ) Cell expands in size and the circular DNA loops move to opposite poles of the cell Cytoplasm begins to divide 2 daughter cells produced

Question 36

Magnification Definition

Answer 36

How much bigger the image is than the specimen

Question 37

Resolution Definition

Answer 37

How well a microscope can distinguish between 2 points that are close together

Question 38

Magnification Equation

Answer 38

Image size ————— Size of real object

Question 39

How do light microscopes work and all about them

Answer 39

They use light to form an image Only larger organelles can be viewed like ribosomes ER and lysosomes Low resolution Low magnification

Question 40

Electron microscopes in comparison to light

Answer 40

Electron microscopes have a higher resolution and higher magnification so give a more detailed image

Question 41

How do TEMS work

Answer 41

Use electromagnets to focus a beam of electrons which are then transmitted through the specimen This allows denser parts of the specimen to absorb more electrons so appear darker

Question 42

+ and - of TEMS

Answer 42

High resolution Can view internal structure of organelles Only used on thin specimens

Question 43

How do SEMs work

Answer 43

Scan a beam of electrons across the specimen which knocks off electrons from the specimen. These are gathered in a cathode ray tube to form an image

Question 44

+ and - of SEMS

Answer 44

3D Can be used on thick specimens Give lower resolutions

Question 45

How to view specimens using an optical microscope

Answer 45

Pipette small drop of water onto the slide Place a thin section of specimen on slide using tweezers Add a drop of stain Add the cover slip by tilting the slip and slowly lowering it to prevent air bubbles from forming

Question 46

Cell fractionation Steps

Answer 46

Grind the cells in a blender for homogenisation. Solution must be kept in a cold isotonic buffer solution Filter large debris out Ultracentrifugation by placing solution in a centrifuge and spin at a low speed. Take tube out and filter out the supernatant. Place supernatant in another tube and spin in centrifuge at a higher speed

Question 48

Why cant we see structure of granules with an optical light microscope

Answer 48

Lower resolution So wavelength of light is too long