Biological Science Exam #2

Professor Beers - JBU

What are the three dietary macronutrients?

Carbohydrates, Proteins, and Fats

What foods are rich in carbohydrates?

Fruits/Vegetables, Grains, and Legumes

What foods are rich in protiens?

Meats, Legumes, and Dairy

What foods are rich in fats?

Dairy, Meats, and Oils

Which category of biological macromolecules is not a macronutrient?

Nucleic Acids

Why must a healthy diet include a variety of food sources?

To ensure that your body receives all necessary
macronutrients

Examples of Vitamins

Vitamins B12, C, or Folate

Examples of Minerals

Sodium, Potassium, Iron, Calcium

What is a mineral?

A inorganic chemical element required by organisms for normal growth, reproduction, and tissue maintenance

What is a vitamin?

An organic molecule required in small amounts for normal growth, reproduction, and tissue maintenance

What are the problems that come from excess mineral intake?

Constipation, risk of type 2 diabetes, kidney stones, high blood pressure, heart failure, or muscle weakness

What are the problems that come from excess fat-soluble vitamin intake?

Headaches, intestinal pain, bone pain, kidney damage, fatigue, headaches, blurred vision, diarrhea, liver damage, or anemia

What is the subunit of carbs?

simple sugars

What is the subunit of fats?

fatty acids and glycerol

What is the subunit of protein?

amino acids

What are the key functions of simple sugars and what are they used to make in the cell?

Energy storage and cell-surface molecules

What are the key functions of amino acids and what are they used to make in the cell?

Enzymes and structural proteins

What are fatty acids/glycerol used to make in the cell?

Phospholipids for membranes

What is an essential nutrient?

Nutrients that can’t be made by the body, so they must be obtained from the diet

Why is it important for vegans/vegetarians to eat a variety of sources of plant proteins?

Because animal products are often the richest source of amino acids

What is an enzymes effect on activation energy?

an enzyme lowers activation energy, increasing the rate of a reaction

Define a catabolic reaction

a chemical reaction that uses an enzyme to break bonds of a substrate

Define an anabolic reaction

a chemical reaction that uses an enzyme to build molecules

What is the role of micronutrients in enzyme function?

Micronutrients serve as a “cofactor” which activates an enzyme for use

Define Energy

The ability to do work, including building complex molecules

Define Macronutrient

Nutrients that organisms must ingest in large amounts to maintain health

What is starch?

A complex plant carb, made of linked chains of glucose molecules (a source of stored energy)

Define essential amino acids

Amino acids the human body cannot synthesize and must obtain from food

Define metabolism

All biochemical reactions occurring in an organism

What is an enzyme?

A protein that speeds up the rate of a chemical reaction

Define substrate

A molecule to which an enzyme binds and in which it acts

What is an active site?

The part of an enzyme that binds to a substrate

Define activation energy

The energy required for a chemical reaction to proceed (enzymes accelerate reactions by reducing their activation energy)

Define micronutrient

Nutrients (vitamins/minerals) that organisms must ingest in small amounts to maintain health

Define cofactor

An inorganic substance (vitamins/minerals) that are required to activate an enzyme

Define chemical energy

Potential energy stored in the bonds of biological molecules

Define conservation of energy

The principle that energy cannot be created or destroyed, and can only be transformed from one form to another

Define potential energy

Stored energy

Define kinetic energy

The energy of motion or movement

Define heat

The kinetic energy generated by random movements of molecules or atoms (lowest form of energy)

Define photosynthesis

The process in which plants use the energy of sunlight to make energy-rich molecules using CO2 and H2O

Define autotroph

Organisms such as plants, algae, and some bacteria that capture the energy of the sun via photosynthesis

Define Chloroplast

The organelle in plant/algae cells where photosynthesis occurs

Define heterotrophs

Organisms that obtain energy by digesting organic molecules that were produced by other organisms

Define light energy

The energy of the electromagnetic spectrum of radiation that is visible to the human eye

Define photons

Packets of light energy, each with a specific wavelength and quantity of energy

Define Chlorophyll

The green pigment present plants that absorbs photons of light energy during the “photo” reactions of photosynthesis

Define ATP

(Adenosine Triphosphate) The molecule that cells use to power energy-requiring functions

Define carbon fixation

The conversion of inorganic carbon into organic forms (ex: CO2 turned into sugars)

Define prokaryote

Single-celled organisms

Define eukaryote

Organisms made of more than one cell

What substances can autotrophs manufacture?

Sugars, complex carbs, proteins, lipids, and nucleic acids

Why are autotrophs so important to the biosphere?

They are the foundation of energy of all life

What is all ATP in photosynthesis used for?

Glucose production

What color of light is least effective in driving the reactions of photosynthesis? Why?

Green light is the least effective in driving the reactions of photosynthesis because chlorophyll reflects green light

What is the equation for photosynthesis?

Sunlight + Water + CO2 (Carbon Dioxide) = O2 (Oxygen) + Glucose

How do electrons flow through the process of photosynthesis?

1. Low energy electrons from water molecules enter the chloroplast

2. Light reactions use electrons to generate ATP and release O2 gas

3. ATP and electrons is picked up by NAD+, the addition of electrons turn it into NADH

4. NADH drops off ATP for carbon reactions from CO2

5. Glucose is generated using the energy from ATP

One of the two key events of light reactions (“photo”synthesis) is Intermediate energy production. What happens during this event?

Photons of light energy hit the chlorophyll molecules inside chloroplasts to energize and then store high energy electrons (e-) & protons (H+) in NAD+ (“taxi cab shuttle”) which becomes NADH and in the process also produces ATP. (The energy outputs from the light dependent reactions are the both ATP and NADH but they never exit the chloroplast)

One of the two key events of light reactions (“photo”synthesis) is the production of oxygen. What happens during this event?

Water molecules are split to keep reloading the lost electrons into the system. This splitting of water also produces oxygen gas (O2) which then exits the cell

While electrons move from light reactions to carbon reactions, what molecule carries them?

NADH picks up electrons, turning it into NAD+

What is the difference between biofuel and fossil fuels?

biofuels are based on plants, and are renewable, but fossil fuels are based on decomposed organisms, and are not renewable

Define glycolysis

A series of reactions that breaks down sugar into smaller units (takes place in the cytoplasm and is the first stage of both aerobic respiration and fermentation)

Define aerobic respiration

a series of reactions that occurs in the presence of oxygen and converts energy stored in food into ATP

What is the citric acid cycle?

A set of reactions that takes place in the mitochondria and helps extract energy (in the form of high-energy electrons) from food (the second stage of aerobic respiration)

What is the electron transport chain?

A process that takes place in mitochondria and produces the bulk of ATP (the third stage of aerobic respiration)

Define fermentation

A series of chemical reactions that takes place in the absence of oxygen and converts some of the energy store in food into ATP (produces far less ATP than aerobic respiration)

What influences the development of obesity?

Genetics, environment, and gut microbes (it is far more complex than just overeating)

How many calories are in one gram of protein?

4 calories

How many calories are in one gram of carbohydrates?

4 calories

How many calories are in one gram of fat?

9 calories

What energy storage molecule is used for short term energy storage, and where is it stored?

Glycogen, which is stored in muscles and the liver

What energy storage molecule is used for long term energy storage, and where is it stored?

Fats/triglycerides, which are stored as fat throughout the body

What is glycogen used for?

Everyday living

What happens if someone runs out of stored glycogen?

Fat is burned and used for energy (fat can only be used once glycogen has run out)

How is ATP used/treated within a cell?

Similar to a form of currency that can “buy” different cell functions

What is the difference between ATP and ADP?

ATP provides energy to a cell, but once the energy is used, it turns into ADP which does not have energy

How are resources given and waste removed from cells?

Through the blood

Where does most of our body heat come from?

The heat given off by metabolism

What are the three major phases of aerobic respiration and where do they occur?

1. Glycolysis (Cytoplasm)

2. Citric Acid Cycle (Mitochondria)

3. Electron Transport Chain (Mitochondria)

What is the equation for aerobic respiration?

Sugar + Water + ADP = CO2, Water, ATP

What happens during glycolysis and what does it produce?

• Glucose is split into 2 pyruvate molecules

• 2 ATP is produced from glucose splitting

• 2 NADH molecules are produced

• No CO2 is produced, no oxygen is needed

What happens during the citric acid cycle and what does it produce?

• 10 NADH is produced (electrons taken from pyruvate

• 2 ATP produced

• 6 CO2 is produced, and leaves the mitochondria

• Oxygen must be present for this cycle to occur

What happens during the electron transport chain and what does it produce?

• The 12 NADH molecules from glycolysis and the citric acid cycle are drop off their electrons, turning the molecule to NAD+

• Electrons are then used to make 36 ATP

• The used and low energy electrons are then picked up by O2 and create water

Why is oxygen so important for the electron transport chain?

Without oxygen, the entire electrons transport chain shuts down. Then only the ATP that is available at that point is the 2 ATP from glycolysis

When does fermentation occur?

When oxygen is scarce or not available to a cell

Why can fermentation support some bacteria but not other organisms?

Fermentation only produces 2 ATP, which is enough energy for some bacteria, but certainly not enough for larger organisms like humans

How much total ATP output is produced by aerobic respiration vs. fermentation?

• Aerobic respiration = 40 ATP

• Fermentation = 2 ATP

What the phrase “energy moves in a downhill direction” mean?

Energy starts from the sun, which is transferred to plants and turned into glucose, which is consumed by organisms, and then released at energy’s lowest form… heat! (Think about the law of conservation of energy)

Define DNA

(Deoxyribonucleic Acid) The molecule of heredity, common to all life forms, that is passed from parents to offspring

Define chromosome

A single, large DNA molecule wrapped around proteins. Chromosomes are located in the nuclei of most eukaryotic cells

Define Genome

One complete set of genetic instructions encoded in the DNA of an organism

Define Nucleotides

The building blocks of DNA. Each nucleotide consists of a sugar, a phosphate and a base (A, C, G, & T)

Define DNA Profile

A visual representation of a person’s unique DNA sequence

What is DNA replication?

The natural process by which cells make an identical copy of a DNA molecule

What is DNA polymerase?

An enzyme that “reads” the sequence of a DNA strand and helps to add complementary nucleotides to form a new strand during DNA replication

Define semi-conservative

DNA replication is said to be semiconservative because each newly made DNA molecule has one original and one new strand of DNA

What is a PCR?

(Polymerase Chain Reaction) a laboratory technique used to replicate, and thus amplify, a specific DNA segment

What are STRs?

(Short Tandem Repeats) sections of chromosome in which DNA sequences are repeated- they are NONCODING meaning they don’t have any genetic information

Define gel electrophoresis

A laboratory technique that separates fragments of DNA by size

How many pairs of chromosomes do humans have?

23 pairs, 46 total chromosomes