Big Idea 3 Vocabulary: Storage of Info

Big Idea 3 Vocabulary: Storage of Info

allele

any of the alternative versions of a gene that produce distinguishable phenotypic effects

alternative splicing

Process by which the exons of the RNA produced by transcription of a gene (a primary gene transcript or pre-mRNA) are reconnected in multiple ways during RNA splicing. The resulting different mRNAs may be translated into different protein isoforms; thus, a single gene may code for multiple proteins. IE if we have exons ABCD we can splice B leaving ACD or we could splice C leaving ABD cc creating

aneuploidy

A chromosomal aberration in which certain chromosomes are present in extra copies or are deficient in number.

cell plate

A double membrane across the midline of a dividing plant cell, between which the new cell wall forms during cytokinesis.

centromere

Area where the chromatids of a chromosome are attached

cleavage furrow

The first sign of cleavage in an animal cell; a shallow groove in the cell surface near the old metaphase plate.

codominance

A condition in which the alleles of a gene pair in a heterozygote are fully expressed thereby resulting in offspring with a phenotype that is neither dominant nor recessive. example: spotted cow

conjugation

in prokaryotes, the direct transfer of DNA between two cells (of the same or different species) that are temporarily joined

crossing over

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

cytokinesis

Division of the cytoplasm during cell division

DNA

(deoxyribonucleic acid) a complex molecule containing the genetic information that makes up the chromosomes.

DNA ligase

A linking enzyme essential for DNA replication; catalyzes the covalent bonding of the 3' end of one DNA fragment (such as an Okazaki fragment) to the 5' end of another DNA fragment (such as a growing DNA chain).

DNA methylation

The biological process by which a methyl group is added to DNA nucleotide. It is essential for the long-term inactivation of genes that occurs during normal cell differentiation in the embryo.

DNA polymerase

Enzyme that builds the complementary strand in DNA replication

DNA replication

the process by which DNA molecule is copied; also called DNA synthesis

epistasis

A situation in which the expression of one gene prevents expression of all allelic forms of another gene, e.g., the gene for male pattern baldness is epistatic to the hair color gene.

euchromatin

The less condensed form of eukaryotic chromatin that is available for transcription.
DNA that is loosely packed around histones. This DNA is more accessible to enzymes and the genes in euchromatin can be activated if needed.

genotype

An organism's genetic makeup, or allele combinations.

helicase

An enzyme that untwists the double helix of DNA at the replication forks, separating the two strands and making them available as template strands.

heterochromatin

A genetically inactive part of the genome

heterozygous

having two different alleles for a given gene

homologous chromosomes

Chromosomes that have the same sequence of genes that have the same structure, and that pair during meiosis. In sexual reproduction, one is contributed by each parent.

homozygous

An organism that has two identical alleles for a trait

incomplete dominance

A pattern of inheritance in which two alleles, inherited from the parents, are neither dominant nor recessive. The resulting offspring have a phenotype that is a blending of the parental traits.

independent assortment

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

inducible operon

usually off, but can be stimulated (induced) when a specific small molecule interacts with a regulatory protein (example lac operon) inducing transcription

kinetochore

A specialized region on the centromere that links each sister chromatid to the mitotic spindle.

lagging strand

A discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each synthesized in a 5' to 3' direction away from the replication fork.

leading strand

The new complementary DNA strand synthesized continuously along the template strand toward the replication fork in the mandatory 5' to 3' direction

linked traits

Traits (genes) that are likely to occur in the same organism because they are located closely on the same chromosome and therefore are less likely to be separated.

lysogenic cycle

a type of phage reproductive cycle in which the viral genome becomes incorporated into the bacterial host chromosome as a prophage and does not kill the host

lytic cycle

a viral reproductive cycle in which copies of a virus are made within a host cell, which then bursts open, releasing new viruses

meiosis

(genetics) cell division that produces reproductive cells in sexually reproducing organisms

nondisjunction

An error in meiosis or mitosis in which members of a pair of homologous chromosomes or a pair of sister chromatids fail to separate properly from each other.

nucleotide

A building block of DNA, consisting of a five-carbon sugar covalently bonded to a nitrogenous base and a phosphate group.

operons

a unit of genetic function found in bacteria and phages consisting of a promoter, an operator, and a coordinately regulated cluster of genes whose products function in a common pathway

phenotype

An organism's physical appearance, or visible traits.

pilus

A long projection on a bacterial surface involved in an attachment, e.g., the sex pilus attaches F+ and F- bacteria during conjugation.

polygenic inheritance

An additive effect of two or more genes on a single phenotypic character.

polyploidy

A chromosomal alteration in which the organism possesses more than two complete chromosome sets. It is the result of an accident of cell division.

purine

Adenine and Guanine, larger in size, contain 2 rings

pyrimidine

Cytosine, Thymine, and Uracil, smaller in size contain 1 ring

repressible operon

transcription is usually on, but can be inhibited (repressed) when a specific small molecule binds allosterically to a regulatory protein (example tryptophan)

RNA

A type of nucleic acid consisting of nucleotide monomers with a ribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and uracil (U); usually single-stranded; functions in protein synthesis, gene regulation, and as the genome of some viruses.

sex-linked traits

Traits controlled by genes located on sex chromosomes.

splicing

Process that involves removal of introns (non-protein coding regions) and the joining of exons (protein coding regions) in a pre-mRNA

synapsis

the pairing and physical connection of replicated homologous chromosomes during prophase I of meiosis

telomere

A region of repetitive nucleotide sequences at each end of a chromatid, which protects the end of the chromosome from deterioration or from fusion with neighboring chromosomes during successive rounds of replication

transduction

(1) a type of horizontal gene transfer in which phages (viruses) carry bacterial DNA from one host cell to another
(2) in cellular communication, the conversion of a signal from outside the cell to a form that can bring about a specific cellular response

transformation

(1) The conversion of a normal animal cell to a cancerous cell. (2) A change in genotype and phenotype due to the assimilation of external DNA by a cell. When the external DNA is from a member of a different species, transformation results in horizontal gene transfer