Oscar's BIO 3 - EXAM 2 Study Guide

What is Energy?

the capacity to do work and drive change in living organisms

What does the first law of thermodynamics state?

Energy cannot be created or destroyed, only transformed.

What does the second law of thermodynamics state?

Energy cannot be created or destroyed; it can only be transferred or transformed.

What molecule is known as the "currency of energy" in cells?

ATP (adenosine triphosphate).

What is catabolism?

The breakdown of complex molecules into simpler ones, releasing energy.

What is anabolism?

The building of complex molecules from simpler ones, requiring energy.

How are catabolism and anabolism related?

Energy released from catabolism is used to drive anabolic reactions.

What is potential energy?

Energy stored in chemical bonds or structures.

What is kinetic energy?

Energy of movement, released when bonds are broken.

What is an exergonic reaction?

A reaction that releases energy; products have lower energy than reactants.

What is an endergonic reaction?

A reaction that requires energy; products have higher energy than reactants.

What does a negative ΔG (Gibbs free energy) indicate?

An exergonic reaction.

What are enzymes made of?

They are typically proteins composed of amino acids.

What is the function of enzymes?

To speed up chemical reactions by lowering activation energy.

What is the "induced fit" model?

The enzyme slightly changes shape to better fit the substrate.

What factors affect enzyme activity?

Temperature and pH

What are the three major energy pathways in cells?

Glycolysis, Krebs cycle (citric acid cycle), and oxidative phosphorylation.

What is glycolysis?

The breakdown of glucose into two pyruvate molecules, producing 2 ATP and NADH.

Where does glycolysis occur?

In the cytoplasm.

What does the Krebs cycle produce?

ATP, NADH, FADH₂, and CO₂.

Where does the Krebs cycle occur?

In the mitochondrial matrix.

What is the role of the electron transport chain?

Uses electrons from NADH and FADH₂ to create a hydrogen gradient that drives ATP synthesis.

What enzyme synthesizes ATP in the ETC?

ATP synthase.

What role does oxygen play in cellular respiration?

It serves as the final electron acceptor, forming water.

Can glycolysis occur without oxygen?

Yes, but it produces less ATP.

What pathways require oxygen?

Krebs cycle and oxidative phosphorylation.

What are the two main stages of photosynthesis?

Light dependent reactions and light dependent reactions

Where does photosynthesis occur?

In the Chloroplast

What are the inputs of photosynthesis?

In the Chloroplast

What are the inputs of photosynthesis?

Sunlight, Water and Carbon Dioxide (Co2)

What are the products of photosynthesis?

Glucose and Oxygen (C6H12O6 + 6O2)

What Pigment Absorbs Sunlight for Photosynthesis?

Chlorophyll

What organelle contains chlorophyll?

The Chloroplast

Where in the chloroplast do light dependent reactions occur?

In the Thylakoid Membranes

Where do light independent (Calvin Cycle) reactions occur?

In the stroma of the chloroplast.

What gives plants their green color?

Chlorophyll Pigments in the Thylakoid Membranes

What are the main inputs of the light dependent reactions?

Light and Water

What are the main products of light dependent reactions?

Oxygen, ATP and NADPH.

Where does the Oxygen released during photosynthesis come from?

The splitting of water during light dependent reactions

What are the inputs to the Calvin Cycle?

ATP, NADPH and Carbon Dioxide (Co2)

What is the product of the Calvin Cycle?

Glucose

Does the Calvin Cycle require light?

No, it occurs without direct light

What are Stomata?

Tiny openings on leaves that regulate gas exchange

What happens to Stomata during the day

They open up to allow Co2 and O2 to enter.

What happens to Stomata at night?

They close down to conserve Water and trapping Oxygen for internal use

What organelle carries out cellular respiration?

Mitochondria

What are the inputs of Cellular Respiration?

Glucose and Oxygen

What are the products of Cellular Respiration?

ATP, Carbon Dioxide and Water

How are photosynthesis and cellular respiration connected?

The products of photosynthesis (glucose and oxygen) are the inputs for cellular respiration, and

vice versa for Carbon Dioxide and water.

What is an autotroph?

An organism that makes its own food through photosynthesis

What is a heterotroph?

An organism that consumes food for energy (eg, animals)

What are somatic cells?

Non-reproductive body cells containing 46 chromosomes in humans.

What are reproductive cells called?

Gametes (sperm and ovum).

What does DNA stand for?

Deoxyribonucleic acid.

What is the difference between DNA and chromosomes?

DNA is the molecule; chromosomes are structures made of DNA and associated proteins.

What are the building blocks of DNA?

Nucleotides made of a phosphate, sugar (deoxyribose), and a nitrogenous base.

What are the four nitrogenous bases in DNA?

Adenine (A), Thymine (T), Cytosine (C), and Guanine (G).

What base pairs are complementary in DNA?

A pairs with T; C pairs with G.

What is a karyotype?

A visual representation of the chromosomes from a cell.

How many chromosomes do humans have in a somatic cell?

46 chromosomes, or 23 pairs.

How are chromosomes categorized in a karyotype?

44 autosomes and 2 sex chromosomes (XX or XY).

What determines biological sex in a karyotype?

XX = female, XY = male.

What is a diploid cell?

A cell containing two sets of chromosomes (e.g., 46 in humans).

What is a haploid cell?

A cell containing one set of chromosomes (e.g., 23 in humans).

Why are gametes haploid?

So that fertilization restores the diploid number.

What is the cell cycle?

The series of events a cell goes through to grow and divide.

What are the main phases of the cell cycle?

G1, S, G2 (interphase) and mitosis (M phase).

What happens during G1?

The cell grows and prepares for DNA replication.

What happens during S phase?

DNA is replicated to produce identical sister chromatids.

What happens during G2?

The cell continues to grow and prepares for division.

What is mitosis?

The division of a cell's nucleus to produce two identical nuclei.

What are the stages of mitosis?

Prophase, Metaphase, Anaphase, Telophase (PMAT).

What happens during prophase?

Chromosomes condense and become visible.

What happens during metaphase?

Chromosomes align at the center of the cell.

What happens during anaphase?

Sister chromatids separate and move to opposite poles.

What happens during telophase?

Nuclear membranes reform around chromosomes.

What is cytokinesis?

Division of the cytoplasm into two daughter cells.

What is G0 phase?

A resting or non-dividing stage for certain cells (e.g., nerve cells).

What are sister chromatids?

Identical copies of a chromosome attached at the centromere.

What is a centromere?

The constricted region where sister chromatids are attached.

How long does mitosis usually take?

Around 80-90 minutes.

What process occurs in reproductive cells to produce haploid cells?

Meiosis

How many chromosomes are in a human haploid cell?

23 chromosomes

What is the chromosome number after fertilization?

46 chromosomes (23 from each parent).

What does diploid mean?

A cell with two sets of chromosomes (2n).

What does haploid mean?

A cell with one set of chromosomes (n).

Which type of cells are haploid in humans?

Gametes (sperm and egg cells).

What is a key difference between mitosis and meiosis?

Mitosis produces two identical diploid cells, while meiosis produces four genetically unique haploid

cells.

What is the main role of meiosis?

To reduce the chromosome number in gametes and create genetic diversity.

How many cell divisions occur during meiosis?

Two — Meiosis I and Meiosis II.

What happens during fertilization?

A sperm cell and an egg cell fuse to form a diploid zygote.

What does fertilization restore?

The diploid number of chromosomes (46 in humans).

What is non-disjunction?

Failure of chromosomes to separate properly during meiosis.

What can non-disjunction lead to?

Chromosomal abnormalities such as trisomy or monosomy.

What is trisomy?

Having an extra copy of a chromosome.

What is translocation?

A chromosomal abnormality where a chromosome segment is moved to another location.

What is Klinefelter syndrome?

A genetic disorder where males have an extra X chromosome (XXY); occurs in about 1 in 1000

males.

What is Jacobs syndrome?

A genetic disorder where males have an extra Y chromosome (XYY); associated with tall stature

and weak muscle tone.

What is Turner syndrome?

A condition where females have only one X chromosome (XO), leading to infertility and

developmental differences.

Who is considered the Father of Genetics?

Gregor Mendel.