Biology Exam 4

Recessive Disorders

Recessive Disorders

Can be carried unnoticed by heterozygotes, and can range from mild (albinism) to severe (cystic fibrosis).

Chromosomes

Autosomal Disorders are disorders not related to ()

Lethal

AA, unlike aa is ()

Dominant Alleles

Alleles with the same phenotypic effect whether present in one or two copies.

Incomplete Dominance

Heterozygotes which exhibit characteristics intermediate between both homozygous conditions. 1:2:1 for Phenotypic and Genotypic ratios.

Codominance

Genes which have more than two alleles in the population, such as the AB blood group.

Pleiotropy

A single gene which influences multiple traits, such as in Sickle-cell Disease.

Sickle-cell Anemia

1/10 of African Americans carry the heterozygote which causes ()

Polygenic Inheritance

Additive effects of two or more genes on a single phenotypic characteristics, such as skin color.

Environmental

Phenotypes, unlike Genotypes, are also influenced by () factors, I.E. Skin Color.

Sex-linked Genes

Genes located on the sex chromosomes; X-linked disorders more likely to occur in males.

Nucleotide, Phosphate

DNA is joined together by covalent bonds between sugar of one () and () of the next.

Expand

In DNA, Nitrogenous bases () from the sugar-phosphate backbone

Nitrogenous Base: Pyrimidines

Single-ring (T & C)

Nitrogenous Base: Purines

Double-ring (A & G)

3D

James Watson and Francis Crick worked out the () Structure of DNA

Helix

DNA has a double ()

Uniform

X-rays showed that the DNA molecule was () in diameter

Chargaff’s Rule

Amount of A=T

Amount of G=C

Hydrogen Bonds

A, T, G, and C are held together by () ()

DNA Replication: Nucleotides

Enzymes use each strand as a template to assemble new () into strands

Semiconservative

The mechanism of DNA Replication is ()

1, 1

Each new double helix consists of () old and () new strand

DNA replication occurs in both directions, and creates () () in return.

Replication Bubbles

6

Humans have over () billion base pairs in 46 chromosomes of DNA.

Genetic

Replication ensures all somatic cells have the same () information

Nucleotides, DNA

The information of an organism’s genotype is carried in sequences of () in ()

Linear

Genetic information (a particular) gene is carried by a () sequence of nucleotides

DNA, RNA

The molecular chain of command is from from () in the nucleus, and () in the cytoplasm.

Transcribed

DNA is () into RNA

Translated

RNA is () into protein

Codons

A sequence of three nucleotides together; Triple code

1

Codons are responsible for coding () of the 20 amino acids.

Transcription

The synthesis of RNA under the direction of DNA

RNA is processed to:

Protect and help it bind to ribosomes

RNA Splicing

Removal of introns and joining of exons to produce a continuous coding sequence.

Introns

New-coding regions

Exons

Coded regions

8

The typical human gene has () exons, which are about 145 nucleotides each.

Match, Codon

Transfer RNAs () amino acids, and match it to a corresponding mRNA ().

Mutations

Any change in the nucleotide sequence of DNA

Mutation

Errors in DNA replication or recombination/mutagens can cause a () of DNA

Base Substitutions

When one base is replaced with another (G turns into A, and changes Gly to Ser).

Mutagenesis

Production of mutations caused by spontaneous errors or a chemical mutagen (physical agent).

Sickle Cell

Mutagenesis can result in diseases such as () ()

Forensics

The scientific analysis of evidence from a crime-scene

Polymerase Chain Reaction

A technique that quickly amplifies a specific segment of DNA

DNA Profiling

Analysis of DNA samples from PCR to determine whether or not the DNA came from the same or a different individual.

Genome

All your DNA

Genetic Markers

Sequences of the genome that vary from person to person.

Genomics

The study of whole genome, in order to give insight into evolutionary relationships.

Function

Genomics provides information on the () of genes.

98

()% of our DNA is noncoding DNA

GMO

Organisms that have acquired one or more genes by artificial means.

Clone

An indvidiual created by asexual reproduction, and genetically identical to a single parent.

Cloning Concerns

Ethical/Religious concerns, lack of genetic diversity, less healthy animals.

Budding

Outgrowth of a new individual from surface of an old one.

Parthenogenesis

Development of unfertilized eggs when conditions are unfavorable for mating.

Population

The unit of evolution is ()

Heritable Traits

Make individuals more likely to survive to survive and reproduction in a certain environment better than individuals that lack those traits

Selective Breeding

The process of selecting a few organisms with desired traits to serve as parents of the next generation

Natural Selection

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.

Common Ancestor

The shared ancestor of new, different species that arose from one population.

Fossil Record

The ordered sequence of fossils as they appear in sedimentary rock layers.

Biogeography

The study of the geographic distribution of species.

Homology

The similarity in structures due to common ancestry.

Comparative Embryology

The study of the similarities and differences in the embryos of different species.

Molecular Biology

The study of heredity at the molecular level.

Adaptations

Changes in physical structure, function, or behavior that allow an organism or species to survive and reproduce in a given environment.

Gene Pool

A total collection of Genes in a population at all times.

Hardy-Weinberg Equilibrium

Occurs when the frequency of each allele in the gene pool remains constant from one generation to the next, meaning NO EVOLUTION occurs unless it’s acted upon by other agents.

Gene Flow

The movement of individuals (gametes) between populations.

Genetic Drift

Change in the gene pool of a population due to chance; can alter allele frequencies in a population.

Bottleneck Effect

An event that drastically reduces population sizes, resulting in a loss of genetic variability and ability to adapt to environmental changes.

Founder Effect

Colonization of a new location by a small number of individuals.

Natural Selection

An environment in which a population adapts to its environment by acting on phenotypes.

Stabilizing Selection

A selection that favors intermediate (balanced) phenotypes.

Directional Selection

A selection that acts against individuals at one of the phenotypic extreme.

Disruptive Selection

A selection that favors populations at both extremes of the phenotypic range.

Intersexual Selection

Selection for mates with specific characteristics.

Intrasexual Selection

Selection of male weapons in order to compete with one another for females.

Zahavi’s Handicap Principle

Secondary Characteristics act as handicaps to males - only superior males can survive such burdens = honest signals of male qualities.

Sexual Dimorphism

The distinction in appearance between males and females of a species.

Compromises

Adaptations are often ()

Microevolutions

Changes in allele frequencies in a population across generations.

Macroevolution

Broad patterns of evolutionary change through time such as speciation and adaptive radiation.

Speciation

The evolution of new species.

Extinction

The irrevocable loss of a species.

Taxonomy

Branch of biology focused on naming and classifying organisms.

Biological Species Concept

Defines a species as a population or group of populations whose members can interbreed and produce fertile offspring.

Ecological Species Concept

Defines a species by its ecological roles or niche.

Phylogeny

Study of the evolutionary relationships between an organism and its known descendants.

Reproductive Barriers

Barriers which isolate a species’ gene pool and prevent interbreeding among species

Prezygotic Barriers

A reproductive barrier formed before a zygote is formed.

Postzygotic Barriers

A reproductive barrier formed after a zygote is formed.

Temporal Isolation

A reproductive barrier where species breed at different times.

Habitat Isolation

Populations live in different habitats and do not overlap .

Behavioral Isolation

When there is little or no sexual attraction between species due to species-specific behaviors.

Mechanical isolation

Female and male sex organs are not compatible.

Gametic Isolation

After mating, gametes do not unite to form a zygote.