biochemistry p2

Question 1

Function of cell wall

Answer 1

A rigid but flexible structure made of cellulose. It acts as a pressure vessel, preventing over-expansion when water enters the cell. It is found in mainly plant cells, but can also be in fungi, algae and some bacteria

Question 2

Function of cell membrane

Answer 2

The entire cell is covered by thus and it is mostly composed of phospholipids. It is ‘selectively permeable’ and controls the entry and exit of various chemical into and out of the cell.

Question 3

Function of flagella

Answer 3

Tail-like projection that helps cells move

Question 4

Cillia

Answer 4

slender protuberances that project from the cell body. (eukaryotic cells only) they can also aid in motion or serve as sensory organelles or clear debris like in the lungs.

Question 5

Mitochondria

Answer 5

Provides energy by producing ATP through cellular respiration

Question 6

Chloroplast

Answer 6

Captures light energy and so is involved in photosynthesis, making glucose (is only found in plant cells since animals injest glucose)

Question 7

Cytoplasm

Answer 7

where most cellular activities occur, like glycolysis and cell division. It also is the space that contains the organelles.

Question 8

Lysosomes

Answer 8

An organelle that breaks down ‘worn out’ organelles, viruses/bacteria and food particles. It does this with digestive enzymes in an acidic environment

Question 9

Ribosomes

Answer 9

They make proteins out of amino acids

Question 10

Centrioles

Answer 10

A structure essential for cell division and the organisation of the spindle fibres in mitosis. Found only in animal cells

Question 11

Rough endoplasmic reticulum

Answer 11

Where many ribosomes are attached, thus it helps synthesize proteins

Question 11

Smooth endoplasmic reticulum

Answer 11

A series of canals that carry materials throughout the cell and help synthesize lipids such as steroids

Question 12

Vacuole

Answer 12

A membrane-surrounded, fluid-filled “storage space containing water, sugar, minerals or enzymes. Function will vary depending on cell type

Question 13

Golgi bodies/apparatus

Answer 13

a structure that stores and packages proteins (such as enzymes) and lipids

Question 14

Nucleus

Answer 14

The small control center of the cell that contains DNA. It also has small ‘pores’ on it that allows materials to enter and exit

Question 15

Nucleolus

Answer 15

A spherical structure of the nucleus that makes ribosomal RNA (rRNA)

Question 16

Chromosomes

Answer 16

Thread-like structures that contain genetic info

Question 17

Intro to membrane transport

Answer 17

• the cell membrane is semi-permeable: some substances can move across the cell membrane while others can’t

Question 18

Concentration gradient

Answer 18

a difference in concentration between one side of the membrane and the other

Question 19

Passive transport

Answer 19

Processes that allow substances to move across the membrane without energy. They use the concentration gradient.
ex. difusion, osmosis and facilitated difiusion

Question 20

Active transport

Answer 20

movement of molecules against a concentration gradient
- requires energy in ATP
- includes active transport (endocytosis and exocytosis)

Question 21

Facilitated diffusion

Answer 21

Large, polar or charged molecules like glucose need to use this because theyre to big to fit between phosphate heads. They use protein channels which are suited to each molecule to get through.

Question 22

Simple difusion

Answer 22

Small non-polar molecules like o2 that can slip between phisphate heads and go through large non-polar portion of the membrane.
- Rate of diffusion is affected by: Molecules size, polarity, charge (charged ions cannot diffuse), temperature and pressure (hot–> faster)

Question 23

Transport proteins

Answer 23

Movement of particles from relatively low to high concentration using a protein carrier

Question 24

Transport requiring vesicles

Answer 24

Membrane assisted

Question 25

Endocytosis

Answer 25

Endocytosis is taking in large or polar macromolecules from outside the cell by engulfing them with their plasma membrane (membrane assisted)`

Question 26

Pinocytosis

Answer 26

“cell drinking”
- the injestion of a liquid into a cell by the budding of small vesicles from the cell membrane

Question 27

Phagocytosis

Answer 27

“cell eating”
- solid particles being taken in by membrane ex. amoeba feeding or an immune system engulfing bacteria to kill it

Question 28

Osmosis

Answer 28

The movement of water from high to low concentration through a semi permeable membrane
- ex. cell in a hypotonic (low solute concentration) solution has water enter it so that solute concentration in the cell is equal to that outside

Question 29

Receptor mediated endocytosis

Answer 29

Receptor proteins on a portion of the cell membrane bind with specific molecules outside the cell. The area containing the proteins us called coated pit, because its coated in a layer of protein.

Question 30

Exocytosis

Answer 30

“reverse pinocytosis”, process where a cell directs the contents of its secretory vesicles out of the cell membrane. These membrane bound vessicles contain soluble proteins to be secreted to the extracellular environment as well as the membrane proteins and lipids that are sent to become components of the cell membrane
ex. releasing a neurotransmitter for cellular communication

Question 31

Isotonic solution

Answer 31

• The ideal cell condition
• Concentration of water : solute is equal
• Water moves in and out of the cell at an equal rate - cell doesn’t expand or shrink

Question 32

What are enzymes

Answer 32

• protein catalysts: they speed up chemical reactions without being consumed
• names often end in “ase”

Question 33

Why are the necessary

Answer 33

• Reactant molecules must collide with enough force and with the correct geometric orientation for bond breaking to occur
  -this happens in a random and uncontrolled manner in non-catalyzed environments (slow)

Question 34

Where does the energy required for chemical reactions come from?

Answer 34

• most chemical reactions get their energy from heat, however, proteins are denatured at high temperatures, so living cells cannot rely on high levels of heat as a source of activation energy
  (activation energy that must be overcome for a chemical reaction to occur)
• The purpose on an enzyme in a cell is to allow the cell to carry out chemical reactions as quickly as possible without using too much energy
• enzymes do this by lowering the activation energy

Question 35

Enzyme structure

Answer 35

• enzymes overcome the activation energy barrier by “holding’ chemical reactants in the correct orientation
• The Substrate is the reactant that an enzyme acts on
• it binds to a particular site on the enzyme called the active site. The active site is where catalysis occurs
• the substrate fits closely into active sites because enzymes cab adjust their shape slightly ti acommodate to the substrate
• This adjustment is referred to as “induced fit” and forms the enzyme-substrate-complex

Question 36

Conditions that help enzymes work their best

Answer 36

enzyme-catalyzed reactions can be saturated
- the speed at which a catalyzed reaction proceeds cannot increase indefinitely by increasing the concentration of the substrate (all active sites get filled)

Every enzyme has an optimal temperature and pH that it works best at due to particle theory and denaturation

• Some enzymes require nonprotein cofactos such as inorganic substances (minerals: ex. Zn and Mn) or organic coenzymes (many Vitamins) before they can work properly

Question 37

Things that inhibit enzymes

Answer 37

• inhibitors are chemicals that bind to specific enzymes
• this results in a change in the shape of the enzyme which shuts it down
• there are two main types of inhibitors: competitive and non-competitive

Question 38

Competitive inhibition

Answer 38

• involves chemical compounds that bind to the active site of the enzyme and inhibit enzymatic reactions. the compounds compete with the true substrate for access to the active site (ex. penicillin)
• similar in shape to substrate

Question 39

Non-competitive inhibition

Answer 39

• an inhibitor molecule binds to the enzyme at a site known as the allosteric site
• as a result the 3D structure of the enzyme is changed, which prevents the substrate from binding to the active site
• molecules that promote the action of enzymes can also bind to allosteric site- they’re called activators

Question 40

Industrial uses of enzymes

Answer 40

the starch processing industry uses enzymatic hydrolysis –> hydrolyzes starch into maltose, then maltose to glucose

The dairy industry uses enzymes to create cheese

Cleaning industry uses enzymes to remove stains at lower temperatures and with less mechanical agitation