Nucleotides and DNA Structure

A comprehensive set of flashcards for studying vocabulary associated with cell biology and genetics.

Prokaryotic Cells

Any unicellular organism that does not contain a membrane bound nucleus or organelles.

Eukaryotic Cells

Any cell that contains a clearly defined nucleus and membrane-bound organelles.

Flagella

A long, whip-like structure that helps in cell movement.

Plasmid

A small, circular piece of DNA found in bacteria and some eukaryotes.

Nucleoid

The region in a prokaryotic cell where the DNA is located.

Pili

Hair-like structures on the surface of some bacteria that help with attachment.

Endoplasmic Reticulum

A network of membranes involved in protein and lipid synthesis; has rough and smooth types.

Rough Endoplasmic Reticulum

Endoplasmic reticulum studded with ribosomes; involved in protein synthesis.

Smooth Endoplasmic Reticulum

Endoplasmic reticulum without ribosomes; involved in lipid synthesis.

Peroxisome

An organelle that contains enzymes that detoxify harmful substances.

Mitochondria

Organelles that generate ATP, the energy currency of the cell.

Microfilaments

Thin, thread-like structures made of actin; involved in cell movement and shape.

Lysosome

Organelles that contain digestive enzymes to break down waste materials.

Microtubules

Cylindrical structures that help maintain cell shape and facilitate movement.

Cytoplasm

The jelly-like substance within a cell that contains organelles.

Cell Wall

A rigid outer layer that provides structural support to plant cells.

Capsule

A protective layer around some bacteria, providing additional defense.

Ribosome

Molecular machines that synthesize proteins from amino acids.

Cell Membrane

A phospholipid bilayer that surrounds and protects the cell, controlling movement in and out.

Vacuole

A storage sac within a cell, larger in plant cells, for nutrients and waste products.

Golgi Apparatus

An organelle that modifies, sorts, and packages proteins and lipids for secretion.

Chromatin

The complex of DNA and protein found in the nucleus; condenses to form chromosomes.

Nucleus

The membrane-bound organelle that contains the cell's genetic material.

Nuclear Envelope

Double membrane surrounding the nucleus.

Nucleolus

A structure within the nucleus where ribosome synthesis occurs.

DNA Replication

The process by which DNA makes a copy of itself.

Transcription

The process of copying a segment of DNA into RNA.

Translation

The process of synthesizing a protein from mRNA.

Reverse Transcription

The synthesis of DNA from an RNA template.

RNA

Ribonucleic acid, a molecule that plays roles in coding, decoding, regulation, and expression of genes.

tRNA

Transfer RNA; helps in translating the RNA code into a protein.

mRNA

Messenger RNA; carries genetic information from DNA to the ribosome.

rRNA

Ribosomal RNA; a component of ribosomes.

Nucleotide

Building blocks of DNA and RNA made up of a sugar, a phosphate group, and a nitrogenous base.

Base Pairing

The specific hydrogen bonding between nitrogenous bases in DNA; adenine pairs with thymine, cytosine pairs with guanine.

Histone

Proteins that help package DNA into nucleosomes, aiding in DNA structure and regulation.

Chromatin Remodeling

The process of altering chromatin structure to regulate gene expression.

Karyotype

A visual representation of an individual's complete set of chromosomes.

Trisomy 21

Also known as Down's syndrome; a genetic disorder caused by an extra chromosome 21.

Operon

A group of structural genes regulated together, typically found in prokaryotes.

Promoter

A DNA sequence that initiates transcription of a particular gene.

Operator

A segment of DNA that a repressor protein can bind to, preventing transcription.

Repressor

A protein that inhibits gene expression by binding to the operator region.

Restriction Enzymes

Enzymes that cut DNA at specific sequences.

Gene

A segment of DNA that contains instructions for making a protein.

Exon

A coding sequence in a gene that is expressed in mRNA.

Intron

A non-coding sequence in a gene that is removed during RNA processing.

Acetylation

The addition of an acetyl group to histones, increasing gene expression by loosening chromatin.

Methylation

The addition of a methyl group to DNA, often leading to gene silencing.

Cytosine

One of the four main nitrogenous bases in DNA, often involved in methylation.

Adenine

A purine base found in DNA and RNA, pairing with thymine in DNA.

Guanine

A purine base found in DNA and RNA, pairing with cytosine.

Thymine

A pyrimidine base found in DNA, pairing with adenine.

Uracil

A pyrimidine base found in RNA, replacing thymine and pairing with adenine.

Gene Regulation

The process of turning genes on or off, affecting the production of proteins.

Mutations

Changes to the nucleotide sequence of DNA that can affect gene function.

Bases

The building blocks of DNA and RNA; adenine, thymine, cytosine, and guanine.

Transcription Factor

Proteins that help regulate the expression of genes by binding to nearby DNA.

Polypeptide

A chain of amino acids that make up proteins.

Nucleus

The organelle that contains the cell's chromosomes and is the site of transcription.

Cytoplasm

The gelatinous fluid inside a cell in which organelles are suspended.

Cell Membrane

The semi-permeable barrier surrounding the cell.

Cell Wall

A rigid layer that provides structure and protection to plant cells.

Vesicle

A small membrane-bound sac that transports substances within a cell.

Endocytosis

The process by which cells take in substances by engulfing them.

Exocytosis

The process of vesicles fusing with the plasma membrane to release their contents outside the cell.

Apoptosis

Programmed cell death, a natural process to remove unwanted cells.

Cell Cycle

The series of phases that a cell goes through before dividing.

Mitosis

The process of cell division that results in two identical daughter cells.

Meiosis

A type of cell division that produces gametes with half the number of chromosomes.

DNA Polymerase

An enzyme that synthesizes new DNA strands by adding nucleotides.

RNA Polymerase

An enzyme that synthesizes RNA from a DNA template during transcription.

Gene Therapy

A technique that uses genes to treat or prevent disease.

Genetic Engineering

The manipulation of an organism's DNA to achieve desired traits.

Transgenic Organism

An organism that has been genetically modified to contain a gene from another species.

Biotechnology

The use of biological processes for industrial and other practical applications.

CRISPR

A technology that allows scientists to edit genes by changing the DNA sequence.

PCR (Polymerase Chain Reaction)

A technique used to amplify small segments of DNA.

Genotype

The genetic constitution of an individual organism.

Phenotype

The observable physical or biochemical characteristics of an organism.

Allele

Different forms of a gene that can exist at a single locus.

Dominant Allele

An allele that masks the effect of a recessive allele in a heterozygous genotype.

Recessive Allele

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

Homozygous

An organism that has two identical alleles for a trait.

Heterozygous

An organism that has two different alleles for a trait.

Genetic Drift

Random changes in allele frequencies in a population.

Natural Selection

The process where organisms better adapted to their environment tend to survive and produce more offspring.

Speciation

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

Biodiversity

The variety of life in the world or in a particular habitat.

Ecosystem

A community of living organisms and their interactions with the environment.

Biomass

The total mass of organisms in a given area or volume.

Food Chain

A series of organisms each dependent on the next as a source of food.

Trophic Level

Each step in a food chain or food web, indicating the position in the energy pyramid.

Ecology

The branch of biology that deals with the relationships of organisms to one another and their physical environment.

Symbiosis

Interaction between two different organisms living in close physical proximity.

Mutualism

A symbiotic relationship where both species benefit.

Commensalism

A symbiotic relationship where one species benefits and the other is neither helped nor harmed.

Parasitism

A symbiotic relationship where one organism benefits at the expense of another.

Carrying Capacity

The maximum population size that an environment can sustain indefinitely.

Ecological Succession

The process of change in the species structure of an ecological community over time.