Genetics Exam 1

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RNA

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Ribonucleic acid- a usually single-stranded polymeric molecule consisting of ribonucleic building blocks. The 3 major types of RNA in cells are rRNA (ribosomal), tRNA (transfer), and mRNA (messenger) which play a role in protein synthesis (translation). In some viruses, RNA is the genetic material.

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allele

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One of 2 or more alternative forms of a single gene that can exist int he same locus in the genome. All of the alleles of a gene determine the same hereditary trait, but each has a unique nucleotide sequence, which may result in different phenotypes.

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amino acid

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Any small molecule/monomer that contains carboxyl group and amino group that bonded together to create polypeptides and proteins.

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centromere

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A specialized region of a chromosome, seen as a constriction under a microscope, that is important to the activities of chromosomes during cell division.

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chromatid

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One of the two visibly distinct replicated copies of each chromosome that becomes visible between early prophase and metaphase of mitosis and is joined to its sister chromatid at their centromeres.

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chromatin

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The DNA-protein complex that constitutes eukaryotic chromosomes and can exist in various degrees of folding or compaction.

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chromosome

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In eukaryotic cells, a linear structure composed of a single DNA molecule complexed with protein. Each eukaryotic species has a characteristic number of chromosomes in the nucleus of its cells. Most prokaryotic cells contain a single, usually circular chromosome.

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complete medium

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For a microorganism, a medium that supplies all of the ingredients required for growth and reproduction, including those normally produced by the wild-type organism.

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central dogma

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DNA --> RNA --> Protein

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transcription translation

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DNA

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Deoxyribonucleic acid- A polymeric molecule consisting of deoxyribonucleotide building blocks that in a double stranded, double helical form is the genetic material of most organisms.

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DNA helicase

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An enzyme that catalyzes unwinding of the DNA double-helix at the replication fork during DNA replication.

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DNA topisomerases

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An enzyme that unwinds supercoils before the replication fork so that the DNA can be separated easily for replication.

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DNA ligase

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An enzyme that catalyzes the formaiton of a phosphodiester bond between the 5' end of one DNA chain and the 3' end of another DNA chain during DNA replication and DNA repair.

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DNA polymerase

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Any enzyme that catalyzes the polymerization of of deoxyribonucleotides into a DNA chain. All DNA polymerases synthesize DNA in the 5'-3' direction.

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DNA polymerase I

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One of several E. Coli enzymes that catalyze DNA synthesis; Originally called the Kornberg enzyme.

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DNA primase

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An enzyme that catalyzes formation of a short RNA primer in DNA replication.

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eukaryote

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Any organism whose cells have a membrane-bound nucleus in which the genetic material is located and membrane bound organelles (e.g. mitochondria). Eukaryotes can be unicellular or multicellular and constitute one of the 3 major evolutionary domains of organisms.

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gene

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The physical and functional unit that helps determine the traits passed on from parents to offspring; also called Mendelian factor. In molecular terms, a gene is a nucleotide sequence in DNA that specifies a polypeptide or RNA. Alterations in a gene's sequence can give rise to species and individual variation.

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genotype

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The complete genetic makeup (allelic composition) of an organism. The term is commonly used in reference tot he specific alleles present at just one or a limited number of genetic loci.

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haploid

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A cell or an individual with one copy of each nuclear chromosome.

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heterozygous

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Describing a diploid organism having different alleles of one or more genes and therefore producing gametes of different genotypes.

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diploid

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A cell or an individual with 2 copies of each chromosome.

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homozygous

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Describing a diploid organism having the same alleles at one or more genetic loci and therefore producing gametes of identical genotypes.

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lagging strand

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In DNA replication, the DNA strand that is synthesized discontinuously from multiple RNA primers in the direction opposite to movement of the replication fork.

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leading strand

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In DNA replication, the DNA strand that is synthesized continuously from a single RNA primer in the same direction as movement of the replication fork.

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Mendelian polulation

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A group of interbreeding individuals who share a common gene pool; the basic unit of study in population genetics.

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messenger RNA

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Class of RNA molecules that contain coded information specifying the amino acid sequence of a protein.

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minimal medium

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For a microorganism, a medium that contains the simplest set of ingredients (e.g. a sugar, some salts, and trace elements) required for growth and reproduction of wild-type cells.

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molecular genetics

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Study of how genetic information is encodes within DNA and how biochemical processes of the of the cell translate the genetic information into the phenotype.

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histone

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One of the basic proteins that are complexed with DNA in chromatin and play a major role in determining the structure of eukaryotic nuclear chromosomes.

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natural selection

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Differential reproduction of individuals in a population resulting from differences in their genotypes.

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nucleosome

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The basic structural unit of eukaryotic chromatin, consisting of two molecules each of the four core histones (H2A, H2B, H3 and H4, the histone octamer), a singles Molecule of the linker histone H1, and about 180 bp of DNA.

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Okazaki fragments

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The short, single-stranded DNA fragments that are synthesized on the lagging-strand template during DNA replication and are subsequently covalently joined to make a continuous strand, the lagging strand.

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origin of replication

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A specific region in the DNA where the double helix unwinds and synthesis of new DNA strands begin.

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phenotype

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The observable characteristics of an organism that are produced by the genotype and it's interaction with the environment.

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population genetics

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Study of the consequences of Mendelian inheritance on the population level, including the mathematical description of a population's genetic composition and how it changes over time.

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prokaryote

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Any organism whose genetic material is not located within a membrane-bound nucleus . Prokaryotes include eubacteria and archaebacteria.

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quantitative genetics

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Study of the inheritance of complex characteristics that are determined by multiple genes.

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replication bubble

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A locally unwound (denatured) region of DNA bounded by replication forks at which DNA synthesis proceeds in opposite directions.

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ribosomal DNA

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The regions of the genome that contain the genes for rRNA in prokaryotes and eukaryotes.

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ribosomal RNA

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Class of RNA molecules of several different sizes that along with ribosomal proteins make up the ribosomes of prokaryotes and eukaryotes.

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sister chromatids

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Two identical copies of chromosomes derived from replication of the chromosome during interphase of the cell cycle. Sister chromatids are held together by the replicated but unseparated centromeres.

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telomerase

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An enzyme that adds short, repeating, noncoding sequence to lengthen telomeres.

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telomere

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The end part of chromosomes that are replicated by telomerases.

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transfer RNA

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Class of RNA molecules that bring amino acids to ribosomes, where they are transferred to growing polypeptide chains during translation.