semester 2 biology finals vocab

Cell Division

Process in which a cell divides into two new daughter cells

Asexual reproduction

Process of reproduction involving a single parent that results in offspring that are genetically identical to the parent

Sexual reproduction

Type of reproduction in which cells from two parents unite to form the first cell of a new organism

Chromosome

Threadlike structure within the nucleus that contains genetic information that is passed on from one generation to the next

Chromatin

Substance found in eukaryotic chromosomes that consists of DNA tightly coiled around histones

Cell Cycle

Series of events in which a cell grows, prepares for division, and divides to form two daughter cells

Interphase

Period of the cell cycle between cell divisions in which the cell grows

Mitosis

Part of eukaryotic cell division during which the cell nucleus divides

Cytokinesis

Division of the cytoplasm to form two separate daughter cells

Prophase

First and longest phase of mitosis in which the genetic material inside the nucleus condenses and the chromosomes become visible

Centromere

Region of a chromosome where the two sister chromatids attach

Chromatid

One of two identical 'sister' parts of a duplicated chromosome

Centriole

Structure in an animal cell that helps to organize cell division

Metaphase

Phase of mitosis in which the chromosomes line up across the center of the cell

Anaphase

Phase of mitosis in which the chromosomes separate and move to opposite ends of the cell

Telophase

Phase of mitosis in which the distinct individual chromosomes begin to spread out into a tangle of chromatin

Cyclin

One of a family of proteins that regulates the cell cycle in eukaryotic cells

Growth factor

One of a group of external regulatory proteins that stimulate the growth and division of cells

Apoptosis

The process of programmed cell death

Cancer

Disorder in which some of the body's cells lose the ability to control growth

Tumor

Mass of rapidly dividing cells that can damage surrounding tissue

Embryo

Developing stage of a multicellular organism

Differentiation

Process in which cells become specialized in structure and function

Totipotent

Cells that are able to develop into any type of cell found in the body (including cells that make up the extraembryonic membranes and placenta)

Blastocyst

Stage of early development in mammals that consists of a hollow ball of cells

Pluripotent

Cells that are capable of developing into most, but not all, of the body's cell types

Stem cell

Unspecialized cell that can give rise to one or more types of specialized cells

Multipotent

Cell with limited potential to develop into many types of differentiated cells

Genetics

Scientific study of heredity

Fertilization

Process in sexual reproduction in which male and female reproductive cells join to form a new cell

Trait

Specific characteristic of an individual

Hybrid

Offspring of crosses between parents with different traits

Gene

Sequence of DNA that codes for a protein and thus determines a trait; factor that is passed from parent to offspring

Allele

One of a number of different forms of a gene

Principle of dominance

Mendel's second conclusion, which states that some alleles are dominant, and others are recessive

Segregation

Separation of alleles during gamete formation

Gamete

A sex cell

Probability

Likelihood that a particular event will occur

Homozygous

Having two identical alleles for a particular gene

Heterozygous

Having two different alleles for a particular gene

Phenotype

Physical characteristics of an organism

Genotype

Genetic makeup of an organism

Punnett square

Diagram that can be used to predict the genotype and phenotype combinations of a genetic cross

Independent assortment

One of Mendel's principles that states that genes for different traits can segregate independently during the formation of gametes

Incomplete dominance

Situation in which one allele is not completely dominant over another allele

Codominance

Situation in which the phenotypes produced by both alleles are completely expressed

Multiple allele

A gene that has more than two alleles

Polygenic trait

Trait controlled by two or more genes

Homologous

Term used to refer to chromosomes in which one set comes from the male parent and one set comes from the female parent

Diploid

Term used to refer to a cell that contains two sets of homologous chromosomes

Haploid

Term used to refer to a cell that contains only a single set of genes

Meiosis

Process in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell

Tetrad

Structure containing four chromatids that forms during meiosis

Crossing-over

Process in which homologous chromosomes exchange portions of their chromatids during meiosis

Zygote

A fertilized egg

Transformation

Process in which one strain of bacteria is changed by a gene or genes from another strain of bacteria

Bacteriophage

Kind of virus that infects bacteria

Base Pairing

Principle that bonds in DNA can form only between adenine and thymine and between guanine and cytosine

Replication

Process of copying DNA prior to cell division

DNA Polymerase

Principle enzyme involved in DNA replication

Telomere

Repetitive DNA at the end of a eukaryotic chromosome

RNA

Single-stranded nucleic acid that contains the sugar ribose

Messenger RNA

Type of RNA that carries copies of instructions for the assembly of amino acids into proteins from DNA to the rest of the cell

Ribosomal RNA

Type of RNA that combines with proteins to form ribosomes

Transfer RNA

Type of RNA that carries each amino acid to a ribosome during protein synthesis

Transcription

Synthesis of an RNA molecule from a DNA template

RNA polymerase

Enzyme that links together the growing chain of RNA nucleotides during transcription using a DNA strand as a template

Promoter

Specific region of a gene where RNA polymerase can bind and begin transcription

Intron

Sequence of DNA that is not involved in coding for a protein

Exon

Expressed sequence of DNA; codes for a protein

Polypeptide

Long chain of amino acids that makes proteins

Genetic code

Collection of codons of mRNA, each of which directs the incorporation of a particular amino acid into a protein during protein synthesis

Codon

Group of three nucleotide bases in mRNA that specify a particular amino acid to be incorporated onto a protein

Translation

Process by which the sequence of bases of an mRNA is converted into the sequence of amino acids of a protein

Anticodon

Group of three bases on a tRNA molecule that are complementary to the three bases of a codon of mRNA

Gene expression

Process by which a gene produces its product and the product carries out its function

Mutation

Change in the genetic material of a cell

Point mutation

Gene mutation in which a single base pair in DNA has been changed

Frameshift mutation

Mutation that shifts the 'reading frame' of the genetic message by inserting or deleting a nucleotide

Mutagen

Chemical or physical agents in the environment that interact with DNA and may cause a mutation

Polyploidy

Condition in which an organism has extra sets of chromosomes

Operon

In prokaryotes, a group of adjacent genes that shares a common operator and promoter and are transcribed into a single mRNA

Operator

Short DNA region, adjacent to the promoter of a prokaryotic operon, that binds repressor proteins responsible for controlling the rate of transcription of the operon

RNA Interference

Introduction of double-stranded RNA into a cell to inhibit gene expression

Homeotic gene

A class of regulatory genes that determine the identity of body parts and regions in an animal embryo

Homeotic gene

A class of regulatory genes that determine the identity of body parts and regions in an animal embryo. Mutations in these genes can transform one body part into another.

Homeobox gene

genes that code for transcription factors that activate other genes that are important in cell development and differentiation

Hox gene

a group of homeotic genes clustered together that determine the head to tail identity of body parts in animals. All hox genes contain the homeobox DNA sequence.

Genome

Entire set of genetic information that an organism carries in its DNA

Karyotype

Micrograph of the complete diploid set of chromosomes grouped together in pairs, arranged in order of decreasing size

Sex chromosome

One of two chromosomes that determines an individual's sex

Autosome

Chromosome that is not a sex chromosome; also called autosomal chromosome

Sex-linked gene

A gene located on a sex chromosome

Pedigree

Chart that shows the presence or absence of a trait according to the relationships within a family across several generations

Nondisjunction

Error in meiosis in which the homologous chromosomes fail to separate properly

Restriction enzyme

Enzyme that cuts DNA at a sequence of nucleotides

Gel electrophoresis

Procedure used to separate and analyze DNA fragments by placing a mixture of DNA fragments at one end of a porous gel and applying an electrical voltage to the gel

Bioinformatics

Application of mathematics and computer science to store, retrieve, and analyze biological data

Genomics

Study of whole genomes, including genes and their functions

Selective breeding

Method of breeding that allows only those organisms with desired characteristics to produce the next generation