CELL PROCESSES NCEA LEVEL 2 BIOLOGY

What is photosynthesis?

plants using light energy to make chemical energy / sugar /glucose

photosynthesis equation

water + carbon dioxide →  glucose + oxygen (in the presence of light)

which organelle does photosynthesis occur in

Chloroplasts

where does Light dependent phase occur

thylakoid/Grana

where does Light INdependent phase occur

Stroma

What processes occurs in light dependent phase

water splits into hydrogen and oxygen, using energy from sunlight

What processes occurs in light INdependent phase

combines Hydrogen and CO₂ in the Calvin Cycle

Where are Chloroplast found in the cell

in the edges of the cell, to access more sunlight

What are the main parts of the chloroplast

1. double lipid membrane

2. stacks of thylakoid (Grana/Granum)

3. liquid called stroma

Factors that affect photosynthesis

• light intensity

• number of chloroplasts

• water availability

• chlorophyll concentration

• Temperature

Structures that are adapted for photosynthesis

1. Chlorophyll / thylakoid membranes / grana absorb light / where light reactions happen.

2. Stroma has light independent reactions / captures carbon / is clear.

3. Double membrane (around chloroplast) is clear to allow light through, it also controls what goes in and out of chloroplast.

4. Plants in the shade have bigger chloroplasts or more chloroplasts than plants in high light areas.

Drawing of Chloroplast

definition of respiration

the process that releases energy (ATP) from glucose / sugar. It can occur aerobically or anaerobically.

what are the two types of respiration

anaerobic and aerobic

where does anaerobic respiration take place

in the cytoplasm of an animal / plant cell

anaerobic respiration equation

Glucose → lactic acid + (2) ATP

where does aerobic respiration take place

starts in cytoplasm, then finishes in the mitochondria

aerobic respiration equation

oxygen + glucose → carbon dioxide + water + ATP

PRO and CONS of anaerobic respiration

- Lactic Acid

- Less ATP per glucose molecule

+ Fast production of ATP

+ does not require oxygen

PRO and CONS of aerobic respiration

+ No Lactic Acid

+ More ATP per glucose molecule

- slow production of ATP

- requires oxygen

Drawing of Mitochondria

Glycolysis meaning

Glucose is broken down to pyruvate

what is ATP

an energy currency that moves around

Passive transport meaning

Does not use ATP to transport substances

Diffusion

Process where particles move from an area of high concentration to an area of low concentration, resulting in even distribution of substances.- Down the gradient

Facilitated diffusion

Passive transport of molecules across a cell membrane with the help of transport proteins, moving from high to low concentration.

Osmosis

the movement of water molecules across a selectively permeable membrane from an area of higher water concentration to an area of lower water concentration.

Active transport

Cells pump substances against concentration gradient USES ATP

What are enzymes

proteins that act as a biological catalyst / speed up biological reactions by lowering the activation energy. They are specific to a reaction.

are enzymes used up in the reaction?

no

How do enzymes work as a catalyst

by lowering the activation energy needed for a chemical reaction to occur, speeding up the process without being consumed.

What two main things bonded are needed for enzymes to work

enzymes and substrates bind together

How do enzyme and substrate bond

Lock and key: enzyme and substrate behave like a lock and key, the enzyme has an active site of a specific shape that fits a specific substrate.

Induced fit: enzymes are able to change their shape so the substrate fits into their active site.

What are enzyme inhibitors

molecules that bind to enzymes and decrease their activity, either reversibly or irreversibly, by blocking the active site or changing the enzyme's shape.

What 2 types of enzyme inhibitors are there

Competitive and non-competitive

what are competitive inhibitors

they bind to the active sight and block the substrate from bonding to the enzyme active site. This prevents the enzyme from catalysing a reaction, which will lower rate of reaction

what are non-competitive inhibitors

Non-competitive inhibitors bind to an allosteric site on an enzyme, causing a conformational change that reduces the enzyme's activity without competing with the substrate.

what are cofactors

Cofactors are inorganic ions or organic molecules that assist enzymes in catalysing reactions by stabilising the transition state or participating in the reaction.

what happens when enzymes get above the optimum temperature

Enzymes denature when exposed to temperatures above their optimum, causing them to lose their shape and function. It overwhelms proteins holding enzyme together. ROR decreases

what happens when enzymes get below the optimum temperature

Enzymes slow down or become less efficient when the temperature drops below the optimum range, leading to a decrease in chemical reactions. There are less collisions between substrate and enzyme

What happens when enzymes are exposed to Low pH

Enzymes denature when exposed to low pH levels. This disrupts their structure, affecting their function and ability to catalyze reactions effectively.

What happens when enzymes are exposed to high pH

Enzymes denature as the excess H30+ ions interfere with the bonds that hold the enzyme together

How does the size of cells affect transport which relates to SA:V ratio

Cells  can only grow to a certain size before the SA:V ratio becomes too small to support rapid transport of materials throughout the cell. 

What is the purpose of DNA replication

DNA replication is to replicate the cells’ DNA in preparation for cell division. Replicated DNA is passed on to daughter cells, ensuring the new daughter cells carry out the same function as parent cells.

What is the purpose of mitosis

parent cell divides into two daughter cells. It occurs in somatic / body cells as part of the cell cycle. The daughter cells are identical to the parent cell. Cells divide for growth and repair as well as to maintain large surface area to volume ratio.

Steps of DNA replication

1. DNA uncoils and unzips (an enzyme does this)

2. Bases are added by another enzyme to each unzipped strand according to the base pairing rule (A-T & G-C)

3. The leading strand is copied continuously 

4. The lagging strand is copied in parts called Okazaki fragments

5. Two identical strands of DNA are produced.

Steps of mitosis

1. Chromosome replicate (copy)

2. Replicated chromosomes line up in the middle of the cell

3. Spindle fibres attach to the centromere of the chromosomes

4. Chromosomes are pulled apart to each end of the cell

5. The cell divides into two identical cells.

Drawing of nucleotide

As cells grow, SA:V _____

decreases

Why is keeping SA:V high important to diffusion

The cell membrane controls the entry and exit of materials into a cell. Diffusion takes place at the cell membrane; therefore a decrease in surface area would decrease the movement of materials into and out of the cell. Diffusion also occurs within the cell, and if a cell’s volume grows too large, the transport of substances within the cell will be inefficient.

Hence, cells divide to keep high SA : V

aerobic respiration steps

1. Glycolysis

2. Pyruvate Oxidation

3. Krebs cycle

4. Electron transport

Cofactor

Non-protein chemical attached to an enzyme and is required for the enzyme assisted reaction to take place

Where to cofactors and noncompetitive inhibitors attach to

Allosteric site