BIO 120: Quiz 5

What are carbohydrates?

• macromolecules that include sugars

• monosaccharides, disaccharides, and polysaccharides

• provide energy

• formula is (CH₂O)_n where “n” is the number of carbon atoms

Where are carbohydrates broken down?

Begins in the mouth then takes place in the small intestines

What enzymes are used to break down carbohydrates?

• Starch and glycogen are broken down into glucose by amylase and maltase

• Sucrose and lactose are broken down by sucrase and lactase.

When the body has excess ATP and glucose what happens to it?

glucose is stored in the liver as glycogen

What are calories?

A unit of measurement for energy that food provides

Define the basal metabolic rate (BMR)

the amount of energy (calories) the body requires at rest to maintain vital functions

How are carbohydrates converted into ATP energy?

Glycolysis: glucose is converted to pyruvic acid which converts into ATP in the mitochondria

Krebs Cycle: Pyruvate is converted into acetyl-CoA and yields ATP

Glucose is an example of ___

monosaccharide

Sugar is stored in plants as ___ and in animals as ____

Starch (in seeds and roots) and glycogen (in liver/muscle cells)

Monosaccharides

are simple sugars (glucose) and exist as a linear chain or as ring-shaped molecules

Polysaccharides

a long chain of monosaccharides linked by covalent bonds (starch, glycogen, and cellulose)

Disaccharides

when two monosaccharides lose a water molecule (examples are lactose, maltose, and sucrose)

What is the primary role of salivary amylase in digestion?

Breaks down polysaccharides into disaccharides in the mouth

What is the structure of a fat molecule (triglyceride)?

Made up of glycerol (C3H3O3) and 3 fatty acid chains that are attached to the glycerol

Saturated Fats

• Fatty acids with single bonds

• saturated with hydrogen

• usually solid at room temperature

• typically from animals

Unsaturated Fats

• Fatty acids with double bonds that prevent them from packing tightly

• liquid form at room temperature

• usually from plants but sometimes animals (fish oil)

• ex: canola, avocado, olive oils

What is an essential fatty acid and what is the source?

Cannot be made by the body, must be consumed through food

What is the structure of a steroid?

Have a four, linked carbon rings and several steroids, like cholesterol, have a short tail.

Describe the process of lipid metabolism (lipolysis)

1. fatty acids undergo beta oxidation

2. glycerol goes under glycolysis

3. Forms acetyl-CoA

4. Enters the Krebs cycle to make ATP energy

What are ketone bodies and what are they used for?

when there’s excessive acetyl CoA, the liver converts it to ketone bodies that serve as fuel if glucose levels get too low

What happens to fats after we eat them?

Broken down into fatty acids and stored in fat cells or used as energy via fatty acids.

What is the structure and functions of proteins?

• most abundant organic molecule

• diverse array of functions including transport, storage or membranes/enzymes

• ex: hemoglobin, collagen, and actin

What is the structure of amino acids?

Monomers that consist of a central carbon atom bonded to an amino, carboxyl, hydrogen atom, and an R group

List all the essential amino acids

• isoleucine

• leucine

• lysine

• methionine

• phenylalanine

• tryptophan

• valine

• histidine

• threonine

• arginine

What traits do all lipids have in common?

Hydrophobicity, nonpolar, insoluble, and monomers

Which of the following best describes a saturated fat?

the fatty acid chain has the maximum number of hydrogens

What do cholesterol, estrogen, and testerone all have in common?

All are steroids

The process of breaking down and digesting fatty acids into acetyl CoA is called

beta oxidation

What are the monomeric units of proteins?

amino acids

Insulin is activated during which metabolic state?

absorptive state

Absorptive State

• can last up to 4 hours after a meal

• your body stores fats and builds glycogen

• the rise of blood sugar levels activates insulin

Post-Absorptive State

• the “fasting state” overnight or when you skip meals

• when food has been digested, absorbed, and stored

• the hormone glucagon is released from the pancreas

Starvation

• the body uses ketones to function due to low blood sugar

• uses Krebs cycle to make ATP

• survival depends of the amount of fat and protein stored in the body

Where are lipids digested?

Begins in the stomach and mouth then goes to small intestines

What enzyme breaks down proteins?

pepsin

Which enzyme breaks down fat?

lipase

How are proteins digested?

first in the stomach with the enzyme pepsin then in the small intestines using pancreatic enzymes to break down the peptides

Which enzyme breaks down carbohydrates?

amylases

Where is insulin and glucagon synthesized?

both are made and released by the pancreas

When digesting fat, what is the role of bile?

emulsification large fat globs

which type of biomolecule is cholesterol?

Lipid

what’s an example of a saturated fatty acid?

Butter

What is the primary function of insulin in the body?

It decreases blood sugar levels by activating the GLUT transporter to allow sugar to enter the cell’s bloodstream

where in the body is cholesterol synthesized?

liver

Which of the following is not a natural source of carbohydrates?

meat products

Which is the correct order of how food gets processed in our body? 

mouth, esophagus, small intestines, large intestines, rectum, stomach

why do fats yield more energy than carbohydrates during metabolism?

because fat molecules contain more carbon-hydrogen bonds, which store more chemical energy

What is the primary function of glucagon?

If blood sugar levels decrease too much, glucagon is a hormone released to make blood sugar levels rise

Why is emulsification important?

Because smaller lipid globs make it easier for pancreatic lipases to digest them

What kind of environment is optimal to digest proteins?

Acidic environment with a low pH helps to denature protein

Which of the following best describes ketogenesis?

Conversion of fatty acids into ketone bodies during starvation

What is the primary role of pancreatic amylase in digestion?

Break down polysaccharides into disaccharides in small intestines

What are 2 key differences between Type I and Type II diabetes?

• Type I requires lifetime insulin injections while Type II often involves insulin resistance, but one may still have normal insulin levels

• T1D is an autoimmune disease, while T2D is primarily metabolic

Glucose is broken down into pyruvate during which metabolic process?

glycolysis

What is characterized by insulin resistance?

Type II Diabetes

There are ___ total amino acids and ___ essential amino acids.

20, 10

After eating, an animals’s blood glucose levels…

Increase

What enzyme is NOT involved with protein digestion?

amylase

Which condition is characterized by an autoimmune destruction of insulin-producing beta cells in the pancreas, typically developing in childhood or adolescence?

Type 1 Diabetes

What is the role of insulin in Type I and Type II diabetes?

In Type I, the body isn't making enough insulin whereas in Type II, the cells don't respond to insulin

Describe Type I diabetes

• Cause: Autoimmune destruction of pancreatic beta cells → little to no insulin production.

• Onset: Usually childhood or adolescence.

• Management: Requires insulin injections for life.

• Risk Factors: Genetic, autoimmune.

Describe Type II diabetes

• Cause: Insulin resistance → body’s cells don’t respond properly to insulin (levels decline gradually)

• Onset: Usually adulthood

• Management: Lifestyle changes, oral medication, sometimes insulin.

• Risk Factors: Obesity, poor diet, lack of exercise, genetics.