BIOL 4426: Cellular Physiology - Cell Nucleus and DNA Mechanisms

These flashcards cover key terminology and concepts from the lecture notes on cellular physiology, specifically focusing on DNA replication, repair mechanisms, and the cell cycle.

Replication

The process by which a cell duplicates its DNA.

Semiconservative Replication

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

Messelson-Stahl Experiment

An experiment demonstrating the semiconservative nature of DNA replication using isotopes of nitrogen.

E. coli

A model organism in genetics, often used in studies like the Messelson-Stahl experiment.

Replication Bubble

The structure formed during DNA replication with two replication forks.

Origins of Replication

Specific sequences in the genome where DNA replication begins.

Autonomous Replicating Sequence (ARS)

A DNA sequence that allows for the initiation of replication, especially in yeast.

Origin Recognition Complex (ORC)

A protein complex that identifies the origin of replication.

Prokaryotic Cells

Single-celled organisms that usually have a single circular DNA molecule.

Bidirectional Replication

Replication that occurs in two directions simultaneously from the origin.

Leading Strand

The strand of DNA that is synthesized continuously in the direction of the replication fork.

Lagging Strand

The strand of DNA that is synthesized discontinuously in short fragments away from the replication fork.

Primase

An enzyme that synthesizes short RNA primers during DNA replication.

DNA Polymerases

Enzymes that synthesize new DNA strands by adding nucleotides.

PCNA (Proliferating Cell Nuclear Antigen)

A protein that helps to increase the processivity of DNA polymerases.

Okazaki Fragments

Short DNA fragments synthesized on the lagging strand during DNA replication.

DNA Ligase

An enzyme that joins Okazaki fragments on the lagging strand to create a continuous DNA strand.

Topoisomerases

Enzymes that relieve torsional strain ahead of replication forks by cutting the DNA strands.

Telomerase

An enzyme that adds repetitive nucleotide sequences to the ends of chromosomes.

Telomeres

The protective ends of linear chromosomes that prevent genetic material loss during replication.

Cyclin Dependent Kinases (CDKs)

Enzymes that regulate the cell cycle by phosphorylating target proteins.

Cell Cycle Checkpoints

Control points in the cell cycle that assess whether the cell is ready to proceed.

Apoptosis

Programmed cell death that can be triggered by DNA damage or errors in replication.

Mismatch Repair System

A DNA repair system that corrects base pair mismatches during DNA replication.

Excision Repair System

A DNA repair mechanism that removes damaged sections of DNA.

Non-Homologous End Joining (NHEJ)

A repair pathway for double strand breaks in DNA that does not require a homologous template.

Homologous Recombination

A process by which cells exchange DNA segments that have similar sequences.

Holliday Model

A model describing how homologous recombination occurs through a series of steps.

RecA

A protein that facilitates strand invasion and alignment during bacterial recombination.

Rad51

The eukaryotic equivalent of RecA involved in homologous recombination.

Ruv Proteins

Proteins that play a crucial role in resolving Holliday junctions during recombination.

DNA Fidelity

The accuracy of DNA replication, characterized by a low error rate.

Proofreading Activity

The ability of DNA polymerases to correct errors during DNA synthesis.

Nucleotide Changes

Spontaneous modifications to nucleotides that can lead to mutations.

Mutagens

Chemical or physical agents that cause mutations in DNA.

CDK Inhibitors

Proteins that inhibit the activity of cyclin-dependent kinases.

G1 Phase

The phase of the cell cycle where the cell grows and prepares for DNA replication.

S Phase

The phase of the cell cycle where DNA is replicated.

Centromere

The region of a chromosome where sister chromatids are joined.

Chiasma

The point where homologous chromosomes exchange genetic material during meiosis.

Growth Factors

Proteins that stimulate cell division and growth.

Senescence

The process by which cells stop dividing due to telomere shortening.

Cloning

The process of creating a genetically identical copy of an organism.

Genetic Diversity

The variety of different genetic makeups within a population.

Carcinogenesis

The process by which normal cells become cancerous.

Xeroderma Pigmentosum

A condition caused by mutations in genes involved in the excision repair system.

Phosphodiester Bond

The type of bond that links nucleotides in a DNA or RNA strand.

Nucleotide Excision Repair

A DNA repair mechanism that corrects bulky DNA lesions.

Mismatch Recognition Protein

Proteins that identify and bind to mismatched base pairs in DNA.

Cytosine Deamination

A chemical modification leading to a uracil base in place of cytosine.

Thymine Dimer

A covalent link between two adjacent thymine bases in DNA caused by UV radiation.

Apoptotic Pathway

The signaling pathway that leads to programmed cell death.

Cell Division Cycle

The series of events that lead to the replication of cells.

Mutation Accumulation

The process by which genetic mutations build up in an organism over time.

Eukaryotic Cells

Complex cells with membrane-bound organelles and a nucleus.

Prokaryotic Cells

Simpler, single-celled organisms without a nucleus.

mRNA

Messenger RNA, which carries genetic information from DNA to ribosomes.

Gene Targeting

A technique used to manipulate genes within an organism’s genome.

CRISPR-Cas9

A technology used for precise genome editing.

Cell Growth

The increase in cell size and mass prior to division.

Endonuclease

An enzyme that cleaves the phosphodiester bond within a nucleotide chain.

Synthesis Direction

DNA synthesis occurs in a 5' to 3' direction.

RNA Primer

A short RNA strand that provides a starting point for DNA synthesis.

Antibiotic Action

The way antibiotics inhibit bacterial functions, including DNA replication.

Caution in Cloning

The careful consideration of ethical and scientific issues surrounding cloning.

Genetic Material Loss

The phenomenon of losing DNA during cell divisions.

Cell Cycle Regulation

The mechanisms that control the timing and progression of the cell cycle.

Genome Complexity

The degree of variation and structural diversity found in an organism's genome.

Chromosome Translocation

A genetic rearrangement where a segment of DNA is relocated to another chromosome.

Cellular Signaling

The communication processes that govern cellular actions.

Taurine

An amino sulfonic acid that plays a role in several biological processes.

DNA Damage Response

A network of cellular pathways activated in response to DNA damage.

Telomere Shortening

The gradual loss of telomere length with each cell division.

Phenotype

The observable physical characteristics and traits of an organism.

Genomic Sequencing

Determining the sequence of nucleotides in a genome.

Bioinformatics

The application of computational techniques to analyze biological data.

Sanger Method

A method for DNA sequencing based on selective incorporation of fluorescently labeled dideoxynucleotides.

Doubling Time

The time it takes for a population of cells to double in number.

Substrate Specificity

The preference of an enzyme for a particular substrate.

Immunoassay

A biochemical test that measures the presence or concentration of a substance through an immune response.

Ethidium Bromide

A fluorescent intercalating agent used in molecular biology for DNA visualization.

Polymorphism

The occurrence of two or more different alleles at a locus in a population.

Endonucleolytic Cleavage

The breaking of the DNA strand by cutting within the DNA molecule.