Bio 121 chapters 4-6

DNA

The molecule that holds the instructions for all living things, stands for DeoxyriboNucleic Acid.

Double Helix

The structure of a DNA molecule, which consists of two strands twisted around each other.

Nucleotide

The basic building block of DNA, consisting of a sugar, a phosphate group, and a nitrogenous base.

Base Pairing Rules

The rules stating that adenine (A) pairs with thymine (T) and guanine (G) pairs with cytosine (C) in DNA.

Semi-Conservative Replication

A method of DNA replication in which each new DNA molecule consists of one original strand and one new strand.

Transcription

The process of synthesizing RNA from a DNA template.

Translation

The process where ribosomes synthesize proteins using the information encoded in mRNA.

Gene Expression

The process through which information from a gene is used to produce a functional gene product, usually a protein.

Gene Regulation

The process of turning genes on and off, thereby controlling gene expression.

mRNA (messenger RNA)

A type of RNA that conveys genetic information from DNA to the ribosome, where proteins are synthesized.

tRNA (transfer RNA)

The type of RNA that brings amino acids to the ribosome during protein synthesis.

rRNA (ribosomal RNA)

The type of RNA that makes up the ribosome and helps in the synthesis of proteins.

Amino Acid

The building blocks of proteins; each amino acid is specified by a codon in mRNA.

Codon

A three-nucleotide sequence in mRNA that corresponds to a specific amino acid or a stop signal during translation.

Introns

Non-coding regions of RNA that are removed during RNA splicing.

Exons

Coding segments of RNA that are joined together after introns are removed to form mature RNA.

Alternative Splicing

A process that allows a single gene to code for multiple proteins by reorganizing the exons in different combinations.

Signal Transduction Pathway

A series of molecular events and reactions that lead to a cellular response to a signal.

Homeotic Genes

Master control genes that regulate the development of body structures in organisms.

Cancer

A disease characterized by uncontrolled division and growth of abnormal cells.

Gene

A unit of heredity which is transferred from a parent to offspring and determines some characteristic of the offspring.

Allele

Alternate forms of a gene that determine distinct traits.

Character

An inherited feature that varies among individuals.

Trait

Each possible variation of a character.

Dominant

An allele that masks the effect of a recessive allele.

Recessive

An allele that is masked by the presence of a dominant allele.

Homozygous

An organism that has two identical alleles for a given trait.

Heterozygous

An organism that has two different alleles for a given trait.

Codominance

A relationship between two alleles where both are expressed in the phenotype.

Incomplete Dominance

A situation in which one allele does not completely dominate another, resulting in a new phenotype.

Multiple Alleles

More than two alleles exist for a certain gene.

Pleiotropy

The phenomenon where a single gene influences multiple phenotypic traits.

Polygenic Inheritance

A form of inheritance in which multiple genes affect a single trait.

Linked Genes

Genes that are located close together on the same chromosome and tend to be inherited together.

Non-disjunction

The failure of homologous chromosomes or sister chromatids to separate during cell division.

Trisomy 21

A genetic disorder characterized by an extra copy of chromosome 21, commonly known as Down syndrome.

Amniocentesis

A medical procedure used in prenatal diagnosis of chromosomal abnormalities and fetal infections.

Cell Division

The formation of new cells from preexisting cells, which provides for growth, repair, and reproduction.

Asexual Reproduction

A type of reproduction that only requires one parent and produces genetically identical offspring without gametes.

Gametes

Sex cells (sperm and egg) that are haploid and contain only one copy of each chromosome.

Chromosomes

Long strands of DNA located in the nucleus of eukaryotic cells, containing genetic information.

Mitosis

The process of nuclear division during the mitotic phase that results in two genetically identical offspring cells.

Meiosis

A special type of cell division that produces gametes, resulting in four haploid cells.

Interphase

The phase of the cell cycle where the cell performs normal functions and duplicates its chromosomes.

DNA

The genetic material in all living organisms that contains the information necessary for growth, development, and functioning.

Sister Chromatids

Duplicated chromosomes that are joined at the centromere, preparing for cell division.

Crossing Over

A process during meiosis where homologous chromosomes exchange genetic material, leading to genetic variation.

Independent Assortment

The random distribution of maternal and paternal chromosomes during meiosis, contributing to genetic diversity.

Cytokinesis

The final step in cell division that involves the division of the cytoplasm, resulting in the formation of two daughter cells.

Karyotypes

Photographic inventories of chromosomes organized in homologous pairs, used to determine sex and chromosomal abnormalities.

Diploid

A cell that contains two sets of chromosomes, one from each parent.

Haploid

A cell that contains one set of chromosomes, typical of gametes.

Chromatin

The material of which the chromosomes of organisms other than bacteria are composed, consisting of DNA and proteins.

Energy

The capacity to do work; the ability to promote change.

Kinetic Energy

Energy associated with movement.

Potential Energy

Energy due to the structure or location of an object.

Chemical Energy

The energy stored in molecular bonds; a form of potential energy.

First Law of Thermodynamics

Energy cannot be created or destroyed, only transformed.

Second Law of Thermodynamics

Every energy transfer increases the entropy (disorder) of a system.

Photosynthesis

The process by which producers convert solar energy into chemical energy.

ATP

A high-energy molecule that stores and supplies energy for cellular activities.

Cellular Respiration

The process that releases chemical energy stored in sugars, requiring oxygen.

Fermentation

The anaerobic process of obtaining energy from sugar without oxygen.

Glycolysis

The first stage of cellular respiration that splits glucose into pyruvic acid.

Citric Acid Cycle

The second stage of cellular respiration that further breaks down pyruvic acid.

Electron Transport Chain

The final stage of cellular respiration that produces the majority of ATP.

Entropy

The measure of disorder or randomness in a system.

Chlorophyll

The primary pigment in chloroplasts that absorbs light for photosynthesis.

Calvin Cycle

The phase of photosynthesis that uses high-energy molecules to produce sugar.

NADPH

A molecule that shuttles electrons, produced during the light reactions of photosynthesis.

STROMA

The fluid-filled space inside chloroplasts where the Calvin cycle occurs.

Aerobic Respiration

Cellular respiration that requires oxygen.

Anaerobic Respiration

Cellular respiration that occurs without oxygen, such as fermentation.

Glucose (C6H12O6)

A simple sugar that is an important energy source in living organisms.

Lactic Acid Fermentation

A type of fermentation that occurs in muscles when oxygen is scarce.

Alcohol Fermentation

Fermentation that occurs in yeast, producing alcohol and carbon dioxide.

Metabolism

The sum total of all chemical reactions that occur in the body, including anabolism and catabolism.

ATP Production

The generation of ATP through processes like cellular respiration and fermentation.

DNA

Deoxyribonucleic acid, the molecule that carries genetic information.

Mutation

Any change in the nucleotide sequence of DNA.

Codon

A three-nucleotide sequence that codes for a specific amino acid.

Frameshift Mutation

Mutations caused by the insertion or deletion of a nucleotide that shifts the reading frame.

Oncogene

A mutated proto-oncogene that has the potential to cause cancer.

PCR (Polymerase Chain Reaction)

A method used to amplify specific DNA sequences quickly and precisely.

Gene Therapy

The alteration of genes to treat or cure diseases by inserting 'correct' DNA into cells.

Genetically Modified Organisms (GMOs)

Organisms that have acquired one or more genes by artificial means.

Restriction Enzyme

Proteins that cut DNA at specific nucleotide sequences.

Transcription

The process of copying a segment of DNA into RNA.

Translation

The process by which ribosomes read mRNA to synthesize proteins.

Amino Acids

Molecules that are the building blocks of proteins; 20 different types exist.

Cancer

A disease characterized by uncontrolled cell growth due to mutations affecting gene expression.

Nonsense Mutation

A mutation that creates a premature stop codon in the protein-coding sequence.

Gene Cloning

The process of making copies of specific genes.

Tandem Repeats

Short sequences of DNA that are repeated in a genome.

Genetic Engineering

The direct manipulation of genes for practical purposes.

Silent Mutation

A mutation that does not alter the protein produced.

Missense Mutation

A mutation that changes one amino acid in a protein sequence.

DNA Profiling

A technique used to identify individuals by their unique DNA characteristics.

Carcinogen

A substance that promotes the formation of cancer.

Cytosine

A nitrogenous base in DNA that pairs with guanine.