Organisms & Energy and Cell Division

A comprehensive set of flashcards covering key concepts in organisms, energy transformations, cell division, photosynthesis, and cell cycle regulation, structured to aid in exam preparation.

First Law of Thermodynamics

Energy cannot be created or destroyed, only converted from one form to another.

Second Law of Thermodynamics

In an isolated system, the total entropy (disorder) will always increase or remain constant over time.

Endergonic reactions

Reactions that absorb energy; products have more energy than reactants.

Exergonic reactions

Reactions that release energy; reactants have more energy than products.

Trophic levels

Levels in a food chain where energy is transferred from one level to the next.

10% Rule

Only about 10% of energy from one trophic level is transferred to the next.

ΔG

Gibbs free energy change; positive for anabolic and negative for catabolic reactions.

Catabolic reactions

Processes that release energy by breaking down molecules.

Anabolic reactions

Processes that require energy to build higher energy molecules.

Hydrolysis by ATPase

Releases approximately 7.3 kcal/mol of free energy.

Energetic coupling

The use of energy released from one reaction to drive another reaction.

Oxidation

The loss of electrons from a molecule, resulting in the release of energy.

Reduction

The gain of electrons by a molecule, resulting in an increase in energy.

Enzyme

A protein that catalyzes biochemical reactions, regulating energy transfer.

Activation energy (EA)

The energy required to initiate a chemical reaction.

Allosteric site

A site on an enzyme where a molecule can bind and influence enzyme activity.

Cell Division

The process by which a parent cell divides into two or more daughter cells.

Prokaryotic cell division

Occurs via binary fission.

Eukaryotic cell division

Occurs via mitosis and cytokinesis.

Mitosis

The division of somatic (non-reproductive) cells.

Meiosis

The division of germ cells to produce gametes (sperm and egg).

Chromatin

DNA wrapped around proteins called histones; forms chromosomes.

S phase

The stage in the cell cycle where DNA replication occurs.

Sister chromatids

Identical copies of a chromosome, linked by a centromere.

Centromere

The region where sister chromatids are joined together.

Prometaphase

Stage in mitosis where the nuclear membrane breaks down and microtubules attach to chromosomes.

Metaphase

Stage in mitosis where chromosomes align in the center of the cell.

Anaphase

Stage in mitosis where sister chromatids are pulled apart.

Telophase

Stage in mitosis where two nuclei form and the cell prepares to divide.

Cytokinesis

The process during cell division where the cytoplasm divides, forming two daughter cells.

Phragmoplast

Structure formed in plant cells during cytokinesis that guides the formation of the cell plate.

Bivalent

A paired structure of homologous chromosomes during meiosis.

Crossing over

The exchange of DNA segments between homologous chromosomes during meiosis.

Kinetochores

Protein complexes associated with the centromeres that attach to spindle fibers.

Cancer

Uncontrolled cell division leading to the formation of tumors.

Oncogene

A mutated gene that promotes cancerous growth.

Proto-oncogene

Normal gene that can become an oncogene when mutated.

Tumor suppressor genes

Genes that inhibit cell division and prevent cancer.

Cyclins

Proteins that regulate progress through the cell cycle.

Cyclin-dependent kinases (CDKs)

Enzymes that, when activated by cyclins, promote cell division.

G1/S cyclin-CDK complex

Prepares the cell for DNA replication at the end of G1 phase.

S cyclin-CDK complex

Involved in the initiation of DNA synthesis.

M cyclin-CDK complex

Initiates events associated with mitosis.

DNA damage checkpoint

Checks for damaged DNA before the cell enters S phase.

Spindle assembly checkpoint

Ensures all chromosomes are attached to the spindle before mitosis.

p53 protein

A protein that regulates the cell cycle and prevents tumor formation.

Cytokinesis in plant cells

Involves construction of a cell plate to divide the cell.

Mitotic spindle

Structure made of microtubules that separates chromosomes during mitosis.

E. coli replication

A model for understanding prokaryotic DNA replication and cell division.

Karyotype

The number and shape of chromosomes in a cell of a species.

Diploid

A cell with two complete sets of chromosomes.

Haploid

A cell with one complete set of chromosomes.

Reductional division

The division phase in meiosis I where chromosome number is halved.

Equational division

The division phase in meiosis II where chromosome number remains the same.

Cell cycle checkpoints

Regulatory points in the cell cycle that ensure proper division.

Meiotic spindles

Structures that pull homologous chromosomes apart during meiosis.

Binary fission

A method of asexual reproduction in prokaryotes.

Cell plate

A membrane-bound structure that forms during cytokinesis in plant cells.

Fertilization

The union of a sperm and egg to form a zygote.

Genetic material

DNA that carries the instructions for an organism.

Cellular respiration

The process by which cells convert glucose and oxygen into energy.

Photorespiration

A process that uses oxygen and releases carbon dioxide, reducing photosynthetic efficiency.

Photosynthesis

The process by which plants convert light energy into chemical energy.

Plant growth

Requires energy production through photosynthesis.

Energy transformation

The conversion of energy from one form to another (e.g., solar to chemical).

Synthesis of nucleic acids

An anabolic process that constructs nucleotides into DNA and RNA.

Chlorophyll

A green pigment in plants that absorbs light energy for photosynthesis.

Pigments

Molecules that absorb light energy, essential for photosynthetic processes.

Thylakoid membranes

Where light-dependent reactions of photosynthesis occur.

Calvin Cycle

The light-independent reactions in photosynthesis that synthesize glucose.

Visible light

The portion of the electromagnetic spectrum that plants use for photosynthesis.

Photosystem

Protein and pigment complexes that absorb light during photosynthesis.

ATP production

The creation of ATP through energy transformation processes in cells.

Electron transport chain

A series of protein complexes that transfer electrons, generating ATP.

Cellular metabolism

The sum of all biochemical reactions within a cell.

NADH

An electron carrier molecule that stores energy used for ATP production.

FADH2

Another electron carrier involved in the electron transport chain.

Chemiosmosis

The process of ATP generation using the proton gradient across a membrane.

Passive transport

The movement of substances across a cell membrane without energy input.

Active transport

The movement of substances against their concentration gradient, requiring energy.

Endocytosis

The process by which cells engulf substances to bring them inside.

Exocytosis

The process by which cells expel materials in vesicles.

Signal transduction

The process by which cells respond to external signals.

Cell signaling

Communication between cells through signaling molecules.

Hormones

Chemical messengers that coordinate various physiological processes.

Receptors

Proteins that bind signaling molecules, triggering a response.

Gene expression

The process by which information from a gene is used to synthesize proteins.

Proteins

Molecules composed of amino acids that perform a wide variety of functions in living organisms.

Amino acids

Building blocks of proteins, linked by peptide bonds.

Genotype

The genetic makeup of an organism, consisting of its alleles.

Phenotype

The observable traits of an organism, influenced by genotype and environment.

Mutations

Changes in the DNA sequence that can lead to variation in traits.

Evolution

The process by which populations change over time through genetic variation.

Natural selection

Mechanism of evolution whereby individuals with advantageous traits survive and reproduce.

Speciation

The formation of new and distinct species in the course of evolution.

Genetic drift

Random changes in allele frequencies within a population.

Population genetics

The study of genetic variation within populations and its evolutionary significance.

Phylogenetics

The study of evolutionary relationships among biological entities.

Fossils

Preserved remains or traces of ancient organisms that provide evidence for evolution.

Biogeography

The study of the geographic distribution of species and ecosystems.