Biology Finals S2 Vocabulary

Flashcards reviewing key vocabulary and concepts from the Biology Finals S2 study guide.

Purpose of DNA Replication

Ensures that each daughter cell receives identical copies of the genetic material during cell division.

Location of DNA Replication

Occurs in the nucleus during the S phase of the cell cycle.

Semi-Conservative Replication

Each new DNA molecule consists of one original strand and one newly synthesized strand.

Helicase

Unwinds and separates the DNA strands.

DNA Polymerase

Adds complementary nucleotides to the template strand.

Primase

Synthesizes RNA primers to initiate replication.

Ligase

Seals gaps between Okazaki fragments on the lagging strand.

Leading Strand

Synthesized continuously in the 5' to 3' direction.

Lagging Strand

Synthesized discontinuously as Okazaki fragments.

Origin of Replication

Specific sites where DNA replication begins; multiple origins exist in eukaryotic DNA.

Role of Telomeres

Protective caps at the ends of chromosomes that prevent the loss of important genetic information during replication.

Proofreading and Error Correction

DNA polymerase has the ability to correct errors during replication.

Significance of DNA Replication

Essential for genetic continuity and proper cell function.

Purpose of Mitosis

Ensures equal distribution of chromosomes into two genetically identical daughter cells, and functions in growth, repair, and asexual reproduction.

Interphase Stages

G1 (growth), S (DNA replication), G2 (preparation for mitosis).

Prophase

Chromosomes condense, spindle fibers form, nuclear envelope breaks down.

Metaphase

Chromosomes align at the metaphase plate.

Anaphase

Sister chromatids separate and move to opposite poles.

Telophase

Nuclear envelopes reform, chromosomes decondense.

Cytokinesis

Division of the cytoplasm into two cells; involves cleavage furrow in animal cells and cell plate formation in plant cells.

Chromatid

One of two identical halves of a replicated chromosome.

Centromere

Region where sister chromatids are joined.

Kinetochore

Protein structure on chromatids where spindle fibers attach.

Role of Spindle Fibers

Attach to kinetochores and separate chromatids during anaphase.

G1 Checkpoint

Ensures the cell is ready for DNA synthesis.

G2 Checkpoint

Checks for DNA replication errors.

M Checkpoint

Ensures proper chromosome alignment and spindle attachment.

Regulation by Cyclins and CDKs

Cyclins and cyclin-dependent kinases (CDKs) regulate progression through the cell cycle.

Mitosis

Produces two genetically identical diploid cells.

Meiosis

Produces four genetically diverse haploid cells.

Importance of Mitosis

Maintains chromosome number in somatic cells and is essential for tissue repair, growth, and replacement of old cells.

Aneuploidy

Abnormal number of chromosomes (e.g., Down syndrome).

Cancer

Uncontrolled cell division due to faulty regulation.

Purpose of Meiosis

To produce gametes (sperm and egg cells) with half the chromosome number of the parent cell; essential for sexual reproduction.

Diploid (2n)

Cells with two sets of chromosomes (e.g., somatic cells).

Haploid (n)

Cells with one set of chromosomes (e.g., gametes).

Prophase I

Chromosomes condense, and homologous chromosomes pair up (synapsis).

Metaphase I

Homologous chromosome pairs align at the metaphase plate.

Anaphase I

Homologous chromosomes are pulled to opposite poles; sister chromatids remain attached at their centromeres.

Telophase I and Cytokinesis

Nuclear membranes may reform, and the cell divides into two haploid cells

Meiosis II Overview

Similar to mitosis but starts with haploid cells; separates sister chromatids into individual chromosomes.

Prophase II

Chromosomes condense again, and spindle fibers form in each haploid cell.

Metaphase II

Chromosomes align at the metaphase plate in each haploid cell.

Anaphase II

Sister chromatids are pulled apart to opposite poles.

Crossing Over

Homologous chromosomes exchange genetic material, increasing genetic diversity.

Independent Assortment

Random orientation of homologous pairs during Metaphase I, leading to different combinations of maternal and paternal chromosomes in gametes.

Gametogenesis

Process of forming gametes: spermatogenesis produces four viable sperm cells in males, and oogenesis produces one viable egg and three polar bodies in females.

Importance of Meiosis

Reduces chromosome number by half, preventing chromosome doubling in offspring and increases genetic variation.

Nondisjunction

Failure of chromosomes to separate properly, which can lead to aneuploidy (e.g., Down syndrome, Turner syndrome).

Significance of Meiosis in Evolution

Genetic variation from meiosis is the basis for natural selection and evolution and provides the raw material for adaptation.

Gregor Mendel

Conducted experiments on pea plants to understand inheritance patterns.

Law of Segregation

Each organism has two alleles for a trait, which segregate during gamete formation.

Law of Independent Assortment

Genes for different traits assort independently during gamete formation.

Gene

A segment of DNA that codes for a specific trait.

Allele

Different forms of a gene.

Dominant

Expressed when present.

Recessive

Expressed only when both alleles are recessive.

Genotype

The genetic makeup of an organism.

Phenotype

The physical expression of a trait.

Homozygous

Two identical alleles for a trait.

Heterozygous

Two different alleles for a trait.

Punnett Squares

A tool to predict the probability of offspring inheriting specific traits; shows possible genotypes and phenotypes from parental crosses.

Monohybrid Cross

Involves one trait; crossing two heterozygous parents results in a 3:1 phenotype ratio.

Dihybrid Cross

Involves two traits; crossing two heterozygous parents results in a 9:3:3:1 phenotype ratio.

Test Cross

Used to determine an unknown genotype by crossing with a homozygous recessive individual.

Rule of Multiplication

Probability of two independent events occurring together.

Rule of Addition

Probability of either of two mutually exclusive events occurring.

Incomplete Dominance

The heterozygous phenotype is intermediate between the two homozygous phenotypes.

Codominance

Both alleles are expressed equally in the phenotype.

Multiple Alleles

A gene with more than two allele options.

Polygenic Inheritance

Traits controlled by multiple genes, leading to a range of phenotypes.

Epistasis

One gene affects the expression of another gene.

Linked Genes

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

Sex-Linked Traits

Traits determined by genes on the sex chromosomes.

Pedigree Analysis

A chart used to trace the inheritance of traits in a family.

Importance of Mendelian Genetics

Foundation for understanding inheritance and predicting genetic disorders and traits in offspring.

Genetic Disorders

Diseases caused by abnormalities in an individual's DNA that may be inherited or occur due to mutations.

Single-Gene Disorders

Caused by mutations in a single gene.

Chromosomal Disorders

Caused by structural changes or abnormal numbers of chromosomes.

Multifactorial Disorders

Result from interactions between multiple genes and environmental factors.

X-Linked Disorders

Caused by mutations on the X chromosome; more common in males.

Genetic Testing

Identifies mutations in DNA.

Karyotyping

Analyzes chromosomes for abnormalities.

Newborn Screening

Detects certain genetic conditions early in life.

Gene Therapy

Experimental technique that replaces defective genes.

Definition of Biotechnology

The use of living organisms, cells, and biological systems to develop technologies and products for various industries.

Genetic Engineering

The direct manipulation of an organism’s DNA using biotechnology to alter genetic makeup for desired traits.

Gene Cloning

Producing identical copies of a gene for research, medicine, or agriculture.

CRISPR-Cas9 Technology

A powerful gene-editing tool that allows scientists to precisely modify DNA sequences.

Genetically Modified Organisms (GMOs)

Organisms whose DNA has been altered for agricultural or medical purposes.

Gene Therapy

A technique that replaces, removes, or alters defective genes to treat genetic diseases.

Stem Cell Technology

The use of undifferentiated cells to develop specialized cells for medical treatments.

Biopharmaceuticals

Medicines produced using biotechnology.

Bioremediation

The use of microbes to clean up environmental pollutants.

Charles Darwin

An English naturalist who proposed the theory of evolution by natural selection.

Evolution

The process of species changing over time through genetic variation and natural selection.

Natural Selection

The mechanism by which organisms with favorable traits survive and reproduce more successfully than others.

Variation

Differences in traits within a population.

Adaptation

A trait that improves an organism's ability to survive and reproduce in its environment.

Overproduction

Organisms produce more offspring than can survive.