Unit1 Module 1 Cells

Question 0

What is resoloution?

Answer 0

The extent to which one can distinguish between 2 objects very close together. The higher the resoloution, the more detail you can see.

Question 1

What is magnification?

Answer 1

How many times the image is larger than itself

Question 2

Function/structure of nucleus

Answer 2

Where the genetic material is stored (DNA)

Question 3

Function/structure of nucleolus?

Answer 3

Dense centre of nucleolus. Makes RNA and ribosomes.

Question 4

Function/structure of nuclear envelope??

Answer 4

Surrounds nucleus with double membrane. The multiple pores regulate passage of macromolecules but allows free access to smaller molecules.

Question 5

Function/structure of SER?

Answer 5

Involved in the synthesis of lipids

Question 6

Function/structure of RER?

Answer 6

Transport and synthesis of proteins

Question 7

Function/structure of Golgi apparatus?

Answer 7

Modifies proteins from the RER and then packages them into vesicles that can be transported

Question 8

Function/structure of ribosomes?

Answer 8

Site of protein synthesis

Question 9

Function/structure of mitochondria?

Answer 9

Double membrane (highly folded inside) 
Where ATP is produced

Question 10

Lysosomes

Answer 10

Contains powerful digestive enzymes that break down materials

Question 11

Chloroplasts

Answer 11

Site of photosynthesis in plant cells

Question 12

Function/structure of centrioles

Answer 12

Microtubules of protein fibres

Question 13

Describe the production and synthesis of proteins. 6 steps.

Answer 13

MRNA gene for protein is made in the nucleus. It leaves the nucleus and attaches to a ribosome on RER. The ribosome assembles the protein. Proteins are pinched off in vesicles and go to the Golgi apparatus. The Golgi apparatus packages protein ready for release. It is secreted at the cell surface membrane.

Question 14

Prokaryotic cells vs eukaryotic cells (4 things)

Answer 14

• Prokaryotic is much smaller than eukaryotic
• prokaryotic only has one membrane (at the cell surface) and no membrane bound organelles
• even the DNA is not surrounded by a membrane, unlike the nuclear envelope of eukaryotic cells
• cell wall is made of Murien, not cellulose

Question 15

Four roles of membranes?

Answer 15

Separating cell contents from the outside environment
Separating cell components from the cytoplasm
Cell signalling
Regulating the transport of materials in and out of the cell

Question 16

What two words best describe plasma membranes?

Answer 16

Partially permeable

Question 17

The role of phospholipids? (2 things)

Answer 17

The hydrophobic layer formed by the phospholipid tails creates a basic barrier and separates the cell contents from the outside world

Question 18

Role of cholesterol in fluid mosaic model?

Answer 18

Gives the membrane stability as it fits between the fatty acid tails

Question 19

Role of glycolipds/glycoproteins in the fluid mosaic model??

Answer 19

Involved in cell signalling

Question 20

What are the two different proteins in the fluid mosaic model and what are their roles?

Answer 20

Channel proteins - helps the movement of large, hydrophilic substances across the membrane
Carrier proteins - actively moves substances across the membrane

Question 21

How do hormone receptors work?

Answer 21

A hormone molecule binds to a receptor on a target cell because the two have complimentary shapes. This causes the target cell to respond in a certain way.

Question 22

What is diffusion?

Answer 22

The net movement of molecules from an area of high conc to a region of low conc down the concentration gradient

Question 23

Effect of temperature on fluid mosaic?

Answer 23

Increase in temp gives molecules more kinetic energy so they move faster. The increased movement of phospholipids etc makes the membrane leaky allowing substances that normally wouldn’t to enter/leave the cell.

Question 24

What is cell signalling?

Answer 24

Cells communicate with each other by signals

Question 25

Four factors that effect patted rate of diffusion

Answer 25

Temperature - more kinetic energy, so the movement of molecules increases and the ROD increases. Concentration gradient - having more molecules on one wide increases the concentration gradient and the ROD Surface area - ROD increases if there is a greater surface area to diffuse across Distance/thickness - diffusion is slowed down by thick membranes

Question 26

What is active transport?

Answer 26

The movement of molecules across the concentration gradient, requiring ATP

Question 27

How is active transport different from facilitated diffusion?

Answer 27

They use energy in the form of ATP and it is much faster than diffusion.

Question 28

What happens to the carrier protein during active transport? Why is this important?

Answer 28

The shape is changed so the molecule it carries fits on one side of the membrane only.

Question 29

What is the definition of osmosis?

Answer 29

The net movement of water molecules from an area of high water potential to an area of low water potential across a partially permeable membrane.

Question 30

What happens to cells in a high water potential area?

Answer 30

The water molecules will enter the cell by osmosis. In an animal cell, the cell membrane will eventually burst open. A plant cell will remain turgid as the cell wall will prevent it from bursting.

Question 31

What happens to cells in a low water potential area?

Answer 31

The water molecules move out of the cell by osmosis. Plant cells experience plasmolysis, where the cell membrane pulls away from the cell wall. Animal cells shrink and appear wrinkled.

Question 32

What is formed by mitosis?

Answer 32

Two genetically identical nuclei

Question 33

Describe prophase (3 things)

Answer 33

Chromosomes condense Nuclear envelope breaks down The centrioles move to opposite ends to form the spindle

Question 34

What happens in metaphase?

Answer 34

The chromosomes line up and are attached to the spindle thread by their centromeres

Question 35

What happens in anaphase? (Two things)

Answer 35

Chromatids split so there is twice as many chromosomes | The spindle fibres shorted so the chromosomes are pulled towards opposite ends

Question 36

What happens in telophase? (3 things)

Answer 36

Nuclear envelope reforms Chromosomes decondense The whole cell splits to form two new cells

Question 37

Why can't most cells undergo mitosis?

Answer 37

Because of their cell walls

Question 38

How are red blood cells (erythrocytes) differentiated? (3 things)

Answer 38

They have no nucleus, or other organelles like mitochondria. They are packed with haemoglobin and they are biconcave (to increase surface area)

Question 39

How do you calculate the linear magnification of an image?

Answer 39

Magnification = image size/actual size