Biology Chapters 11-14

Monohybrid Cross

Monohybrid Cross

The cross between plants that differ only in one trait

Locus

Physical location of a trait or gene on a chromosome

Dominant Allele

Allele that exerts its phenotype on a heterozygote; masks the expression of the recessive allele

Recessive Allele

Allele that exerts its phenotype on a homozygote; masked by the dominant allele.

Homozygous

Organism with two identical alleles

Heterozygous

Organism with two different alleles at a gene locus

Genotype

An individual's alleles received at fertilization

Phenotype

They physical appearance of an individual; determine d by proteins produced by corresponding alleles

Dihybrid Cross

Cross between plants that differ in two traits

Law of Independent Assortment

Each pair of factors segregates independently of the other pairs, All possible combinations of factors can occur in the gametes

Punnentt Square

Visual representation developed by Reginald Punnett that is used to calculate the expressed results of simple genetic crosses

Testcross

Cross between an individual with a recessive phenotype and an individual with a dominant phenotype to see if it is homozygous or heterozygous dominant

Autosome

Any chromosome other than a sex chromosome

Carriers

Individuals that do not express the genetic disorder in their phenotype but are able to pass it onto their children because they still have it in their genotype

Multiple Alleles

Inheritance pattern in which there are more than two alleles for a particular trait; blood type

Codomiance

Inheritance pattern in which both alleles of a gene are equally expressed in a heterozygote

Single Stranded Binding Proteins (SSB)

Attach to newly separated DNA to prevent it from re-forming the helix so replication can occur

DNA Primase

Places short primers on the strands to be replicated

DNA Ligase

"Glue" that mends okazaki fragments together and recombinant DNA together

Replication Fork

V shape that forms wherever DNA is being replicated

Uracil (U)

Pyrimidine in RNA with a single ring structure; complementary base pairs to Adenine

Messenger RNA (mRNA)

Takes message from DNA in the nucleus to the ribosomes in the cytoplasm

Transfer RNA (tRNA)

Transfers amino acids to the ribosomes

Ribosomal RNA (rRNA)

Makes up the ribosomes where polypeptides are synthesized

Transcription

Process of an RNA molecule being produced based on a DNA template

Translation

mRNA transcript is read by a ribosome and converted into a sequence of amino acids in a polypeptide

Central Dogma of Molecular Biology

Processes that dictate the flow of information from DNA to RNA to protein in a cell; DNA - RNA - Protein; DNA - mRNA - polypeptide

Genetic Code

Universal code that has existed for eons and allows for conversions of DNA and RNA's chemical code to a sequence of amino acids in a proten

Triplet Code

three nucleotides in a genetic code

RNA Polymerase

Joins nucleotides in RNA together in the 5' to 3' direction

Promoter

Sequence of DNA in an operon that RNA polymerase binds to, to begin transcription; they signal the start of the operon and the location of transcription

Incomplete Dominance

Inheritance patter in which offspring have an intermediate phenotype

Incomplete Penetrance

Dominant alleles that are not present or fully expressed

Pleiotropy

When a single mutant gene affects two or more distinct and seemingly unrelated traits

Polygenetic Inheritance

When a single trait is governed by two or more sets of alleles

Multifactorial Traits

Polygenic traits subject to environmental influences

X-Linked

Genes that are carried on the x chromosome

Hemizygous

An individual possessing only one allele for a gene on the x chromosome

Adenine (A)

Purine double ring nucleotide base; complementary base pairs to Thymine

Guanine (G)

Purine double ring nucleotide base; complementary base pairs to Cytosine

Thymine (T)

Pyrimidine single ring nucleotide base; complementary base pairs to Adenine

Cytosine (C)

Pyrimidine single ring nucleotide base; complementary base pairs to Guanine

Double Helix

Double spiral, three dimensional shape of DNA

Complementary Base Pairing

Hydrogen bonding between particular purines and pyrimidines

DNA Replication

Process of copying a DNA molecule

Template

A mold used to produce a shape complementary of itself

Semiconservative replication

Process of DNA replication that results in two double helix molecules each having one parental strand and one new strand

Codon

Also known as a triplet Codon; three nucleotides in a genetic code

mRNA Transcript

mRNA molecule formed during transcription that has a sequence of bases complementary to a gene

Introns

Intervening sequence found between exons in mRNA; removed by RNA processing before translation

Exons

Segment of mRNA containing the protein coding portion of a gene that remains within the mRNA after splicing has occured

Ribozyme

An enzyme made of RNA rather than just protein

Anticodon

A group of three bases that is complementary and anitparallel to a specific mRNA codon

Polyribosome

The entire complex of mRNA and multiple ribosomes

Initiation

The step that brings all the translation components together

Elognation

The stage during protein synthesis when a polypeptide increases in length one amino acid at a time

Termination

The final step in protein synthesis that occurs at a stop codon

Proteomics

The study of the structure, function, and interaction of cellular proteins

Structural genes

The genes that code for the enzymes and proteins that are involved in the metabolic pathway of the operon

Operon

Model to explain gene regulation in prokaryotes

Regulator Gene

Gene that codes for the protein that acts as a repressor to control whether the operon is active or not

Operator

a short portion of DNA located before the structural genes. If the repressor is attached to the it, the operon is not functional

Inducer

Molecule that brings about activity of an operon by joining with a repressor and preventing it from binding to the operator

Chromatin

A stringy material made up of DNA associated with a variety of proteins

Barr Body

Highly condensed chromatin adhering to the inner edge of the nuclear membrane

Epigenetic inheritance

Variations in the pattern of inheritance that are not due to changes in the sequence of the DNA nucleotides

Transcriptional Control

Most critical level of control of gene expression with the use of transcription factors, and other proteins that regulate either the initiation of transcription or the rate at which it occurs

Transcription Factors

Protein required for the initiation of transcription by RNA polymerase

Transcription Activator

Protein that participates in the initiation of transcription by binding to the enhancer regulatory regions

Enhancers

DNA sequence that acts as a regulatory element to increase the level of transcription when regulatory proteins, such as transcription activators, bind to it

Posttranscriptional Control

Gene expression following transcription that regulates the way mRNA transcripts are processed

Micro RNA (miRNA)

Small snippets of RNA that can bind to and disable the translation of mRNA in the cytoplasm

Small-interfering RNA (siRNA)

Type of small RNA that joins with an enzyme to form an active silencing complex, which targets specific mRNAs in the cell for breakdown

RNA Interference

Process of interfering with the normal gene expression pathway

Translational control

Gene expression regulated by influencing the interaction of the mRNA transcripts with the ribosome

Posttranslational Control

Alternation of gene expression by changing a protein's activity after it is translated

Proteases

Enzymes that break down proteins

Proteasomes

Special structures that proteases are typically found in

Gene Mutation

Permanent change in the sequence of bases in DNA

Spontaneous Mutations

Mutations that arise from abnormalities in normal biological processes

Induced Mutations

Mutations that are caused from mutagens

Mutagens

Environmental factors that can alter the base composition of DNA

Carcinogens

Cancer-causing mutagens

DNA Repair Enzymes

One of several enzymes that restore the original base sequence in an altered DNA strand

Point Mutations

A change in a single DNA nucleotide

Frameshift Mutations

One or more nucleotides are added or deleted from the DNA

Gene Cloning

DNA cloning for the purpose of producing many copies

Gene Therapy

The process of using of cloned genes to modify a human

Transgenic Organisms

Non-human organisms that are genetically modified

Recombinant DNA (rRNA)

DNA with tow or more different sources

Vector

A means to transfer foreign genetic material into a cell

Plasmids

Small accessory rings of DNA found in bacteria

Restriction Enzyme

Enzyme the cleaves DNA

Polymerase Chain Reaction (PCR)

Used to accelerate the pace of genetic engineering by quickly creating many clones of a piece of DNA without inserting it into a plasmid

Gel Electrophoresis

Process that separates DNA fragments according to their size

DNA Fingerprinting (DNA Profiling)

Technology used to identify and distinguish among individuals based on variations in their DNA

Short Tandem Repeat Sequences (STRs)

Short DNA sequences that are repeated many times in a row

Genetically Modified Organisms (GMOs)

Transgenic bacteria, plants, and animals

Biotechnology Products

The products that genetically modified organisms produce

Gene Pharming

The use of transgenic farm animals to produce pharmaceuticals