Biochemistry- Unit 3 IB Bio SL

What are three factors that impact enzyme activity?

1. pH, enzymes work at an optimum pH

2. temperature, enzymes work faster as it heats up, them dramatically slow down as it starts to denature

3. substrate concentration, plateaus as more substrate is introduced and reaches maximums speed

How does the body control the secretion of digestive juices so they are only secreted when food is present?

• Combination of nervous system

• Food in stomach stimulates receptors due to stomach stretching

• Stretching causes gastrin production

• Arrival of chyme to the small intestine triggers the release of hormones

• Amount of gastric juices are controlled

Where is lipase, amylase and endopeptidase produced?

• Pancreas

• Pancreas and mouth

• Pancreas

How does anorexia nervosa impact the heart?

• Breaks down and weakens heart muscle

• Low blood pressure

What causes malnutrition and what are its consequences?

Deficient/excess of an essential nutrient, may be related to social or socioeconomic factors (cause)

Starvation can lead to breakdown of body tissues, obesity can lead to health problems such as CHD and diabetes, anorexia can lead to organ failure and other serious health problems (consequences)

Describe the specific functions of proteins

Rubisco- Fixes CO2 from atmosphere during photosynthesis

Insulin- Controls blood glucose levels

Collagen- forms connective tissues and ligaments

Spider silk- Forms spider web

Rhodopsin- Involved in photoreceptor

Antibodies- Attach to pathogens

Myosin- Performs muscle contraction

Hemoglobin- Carries oxygen in red blood cells

What causes enzymes to react with substrates?

Molecules collide with enzymes, the substrate bonds with enzyme active site and they react

What’s the difference between glycogen and starch?

Starch: stored in plants, products of photosynthesis, structural

Glycogen: excess glucose stored in animals in their liver and muscle tissue, energy storage

Outline causes and treatments of PKU

• Phenylketonuria is an inherited condition where phenylalanine hydroxylase is not produced

• Phenylalanine is an essential amino acid

• Body cannot breakdown phenylalanine so it builds up in the body (causes)

• Requires diet low in phenylalanine

• Monitor blood phenylalanine levels

• Monitor growth rates and intellectual development in children (treatment)

What features do the small intestines have that allow for efficient absorption of nutrients and other molecules?

• Very long

• Villi and microvilli, increasing the surface area for more absorption

• Cells of small intestine contain mitochondrion to provide energy (ATP) for active transport across the cell membrane, nutrients can then be absorbed

• Thin villi walls, less distance for diffusion

What are the functions of gastrin, HCL and pepsin?

Gastrin: stimulates production and release of HCL

HCL: lowers pH in the stomach, kills pathogens

Pepsin: digests proteins

Outline the structure of proteins

• Protein formed from amino acids

• Linked together by peptide bonds

• Have a specific 3D shape

• Shape determines function

How does H. pylori cause ulcers?

• Weakens mucus coating, allowing acid to get through to the epithelial layer

• Acid damages stomach wall

Why is it advantageous to use lactase in an immobilized state in the food manufacturing industry?

• Cheaper

• Less likely to denature the enzyme

• More efficient

Describe denaturation and its causes

Denature: enzyme, specifically the active site, loses its specific 3D shape and can no longer bond with its specific substrate

Cause: Extreme temperatures or pH, each enzyme has an optimal temperature and pH, denaturation can be temporary, depending on the level of shape change/bonds broken

How do specific enzymes react with their substrate?

• Enzymes are proteins with a specific 3D shape

• Have an active site that binds with a s specific substrate

• When enzyme-substrate complex is formed, the reaction occurs

• Products are released, and enzyme returns to its original shape to be reused

• Denaturation changes shape, changing the enzyme’s ability to bind with substrate

Why is fiber important in the diet?

• Aids peristalsis

• Reduces risk of intestinal disorders and constipation

• Reduces hunger