BIOL 1020 Exam 3

Photosynthesis

Process that converts solar energy into chemical energy.

Chemotrophs

Organisms that can only get energy directly from chemical compounds.

Phototrophs

Organisms that get energy directly from light.

Photoautotrophs

Organisms that carry out photosynthesis.

Photoheterotrophs

Organisms that use light energy but cannot fix CO2.

Chemoautotrophs

Bacteria that obtain energy from reduced inorganic molecules and use some of it to fix CO2.

Chemoheterotrophs

Organisms that use organic molecules as both carbon and energy sources.

Autotrophs

Organisms that obtain energy directly from the environment and make organic molecules from inorganic molecules.

Heterotrophs

Organisms that get energy and carbon by breaking down organic molecules assembled by other organisms.

Electromagnetic Spectrum

The range of all wavelengths of electromagnetic radiation.

Chloroplasts

Organelles in eukaryotic cells where photosynthesis occurs.

Stroma

The fluid-filled region inside the inner membrane of chloroplasts.

Thylakoids

Disk-like membranous sacs found in the stroma of chloroplasts.

Thylakoid Membrane

The folded inner membrane that makes up thylakoids.

Thylakoid Lumen

The fluid-filled region inside a thylakoid.

Granum

A stack of thylakoids.

Chlorophyll

The main light harvesting molecule found in the thylakoid membrane.

Pigment

An organic molecule that selectively absorbs light of specific wavelengths.

Chlorophyll a

The most common photosynthetic pigment that absorbs violet-blue and red light.

Light Reactions

The phase of photosynthesis that captures light energy, consumes water, and produces oxygen.

C3 Cycle

The cycle in photosynthesis that consumes CO2 and energy to produce carbohydrates.

Carbon fixation

The process of taking carbon from inorganic sources to produce organic molecules.

RuBP

Ribulose 1,5-biphosphate, a 5-carbon compound involved in the C3 Cycle.

3-PGA

3-phosphoglycerate, a three-carbon compound formed during carbon reduction.

Photorespiration

A metabolic pathway that consumes oxygen and releases carbon dioxide, occurring when O2 levels are high.

C4 Plants

Plants that preface the carbon cycle with an alternate mode of carbon fixation forming a four-carbon compound.

CAM Plants

Plants that fix carbon at night, only opening their stomata during the night to conserve water.

Somatic cells

Body cells that are diploid (2n), containing two complete sets of chromosomes.

Gametes

Sex cells (sperm and egg) that are haploid (n), containing one set of chromosomes.

Binary fission

A type of cell division used by prokaryotes for reproduction.

Chromatin

Long DNA molecules associated with proteins in the nucleus.

Chromosomes

Densely packaged chromatin that forms during cell division.

Mitosis

A type of cell division in eukaryotic cells that results in two identical daughter cells.

Prophase

Stage in mitosis where chromatin condenses to form chromosomes.

Metaphase

Stage in mitosis where chromosomes line up along the midplane of the cell.

Anaphase

Stage in mitosis where sister chromatids are pulled towards opposite poles of the cell.

Telophase

Final stage of mitosis where chromosomes decondense and nuclear membranes reform.

Cytokinesis

The process that divides the cytoplasm of a parental cell into two daughter cells.

Endogenous cell signaling

Signals to divide that originate from within the cell.

Exogeneous cell signaling

Signals to divide that are received from outside the cell.

Asexual Reproduction

Reproduction that creates genetically identical offspring, requiring only mitotic division.

Sexual Reproduction

Reproduction that involves the fusion of gametes, creating genetically diverse offspring.

Zygote

A single cell formed by the fusion of two gametes.

Meiosis

The process that halves the number of chromosomes in diploid cells to form haploid gametes.

Synapsis

The pairing of homologous chromosomes during prophase I of meiosis.

Crossing Over

Exchange of genetic material between homologous chromosomes during meiosis.

Independent Assortment

The random orientation of homologous chromosome pairs during metaphase I of meiosis.

Random Fertilization

The concept that any sperm can fuse with any ovum, contributing to genetic variation.

What is the Krebs Cycle also known as?

The Krebs Cycle is also known as the Citric Acid Cycle.

Where does the Krebs Cycle occur in eukaryotic cells?

The Krebs Cycle occurs in the inner space of mitochondria.

How many times does the Krebs Cycle go around for each glucose molecule?

The Krebs Cycle goes around twice for each glucose molecule.

What is the entry point of the Krebs Cycle?

The entry point is the combination of acetyl-CoA and oxaloacetate to form citrate.

What is one side reaction that occurs in the Krebs Cycle?

One side reaction is GTP + ADP = GDP + ATP.

How many enzyme-catalyzed steps are in the Krebs Cycle?

There are eight enzyme-catalyzed steps in the Krebs Cycle.

What is produced from the rest of the Krebs Cycle?

Two CO2, oxaloacetate, and energy are produced.

What is the net gain or loss of oxaloacetate in the Krebs Cycle?

There is no net gain or loss of oxaloacetate in the cycle.

How is energy stored during the Krebs Cycle?

Energy is stored in 3 NADH, 1 FADH2, and 1 ATP for each cycle.

What occurs during oxidative phosphorylation?

Electrons from NADH and FADH2 are transferred to a chain of electron acceptors and eventually to oxygen.

What happens to NADH during oxidative phosphorylation?

NADH is oxidized to NAD, releasing electrons.

What can stop the electron transport chain?

The lack of oxygen or the presence of compounds like cyanide can stop the transport chain.

What is the difference between substrate-level phosphorylation and oxidative phosphorylation?

Substrate-level phosphorylation comes from enzyme activity, while oxidative phosphorylation occurs through the electron transport chain.

What is the overall ATP yield from cellular respiration?

Cellular respiration generates a total of 36 to 38 ATP.

What is unique about anaerobic respiration?

Anaerobic respiration still uses the electron transport chain but uses molecules other than oxygen as electron acceptors.

What does fermentation involve?

Fermentation involves no electron transport chain and is very inefficient, resulting in a net of 2 ATP per glucose molecule.

What happens in lactic acid fermentation?

In lactic acid fermentation, pyruvate is reduced to lactate to regenerate NAD.

Which organisms perform lactic acid fermentation?

Some bacteria, fungi, and animals (especially when muscles need energy quickly) perform lactic acid fermentation.

What primary type of energy source does glycolysis provide?

Glycolysis provides a primary energy source for fermentation.

What is the role of CoA in the entry of the Krebs Cycle?

CoA is released when acetyl-CoA combines with oxaloacetate to form citrate in the Krebs Cycle.