Medical Biology Chapter 6 Study Guide Flashcards

Gene Mutations

Gene Mutations

Change in DNA Sequence of a single gene.

Mutagens

Environmental agents that can change DNA or increase frequencies of mutations

Name the examples of Radiation Mutagens

X-Rays

UV Light (Natural)

Name the examples of Chemical Mutagens

Clean Products

Processed Food

Cosmetics

Carcinogens

Name the examples of Infectious Mutagens

Virus: HPV

Bacteria

What do mutations that are caused by raditation produce?

Cancer (these types of mutations ar enot passed on to offspring)

What do mutations that are caused by infectious agents result in?

HPV can cause cervical cancer

Heliobacter Pylori can cause stomach cancer

Name both types of gene mutations:

Point Mutations

Frameshift Mutations

Silent Mutation

Mutation that changes the codon but does not affect the amino acid sequence.

ex: UGC = Cysteine

UGU = Cysteine

Missense mutations

A mutation that changed the codon and produces a new amino acid

ex: UGC = Cysteine

UCC = Serine

Nonsense Mutations

A mutation that results in a stop codon.

Ex: UGC = Cysteine

UGA = Stop

Frameshift Mutation(Insertion)/ Insertion Mutation

When one or more nucleotides (bases) are added into the codon.

Frameshift Mutation(Deletion)/Deletion Mutation

When one or more nucleotides(bases) are deleted from the DNA sequence.

Trinucleotide Repeat Expansions

During DNA Replication, DNA polumerase may make duplicate copies of DNA sequence that are repeated. When cells divide and DNA is replicated, the expansion continues.

Chromosomal Mutations

Changes in chromosome segments or the whole chromosome.

What may happen during Prophase I, Anaphase I, and Anaphase II that may cause a chromosomal mutations?

Chrossing over may result in one chromosome getting more genetic materials and the other less. Mutations that are caused here are passed down to offspring.

Genome Duplication

This occurs during anaphase of mitosis, where one cell will get both sister chromatids.

Gene Translocation

When a segment of one chromosome moves to a nonhomologous chromosome (crossing over occurs in prophase I of meiosis I or prophase of mitosis)

Balanced Translocation

When the exchange is reciprocated and there is no gain/loss in genetic material.

Nondisjuction Mutations

When one or more homologous chromosomes do not separate during Anaphase I of Meiosis I.

What is a positive effect of mutations?

Mutations can enhance the organism’s survival;

ex: improved reproduction rate

Mutations within germ cells are…

…passed on

Mutations within Somatic cells are…

…not passed on

Promoter

This is a site at the beginning of a DNA that initiate transcription.

Enhancer

Short segment of DNA that makes transcription go faster.

TATA Box

A DNA sequence that indicates where genetic sequence is read and decoded

RNA Polymerase

Enzyme that is responsible for copying the DNA into RNA during transcription

Where does the majority of genetic diversity occur?

When there are mutations within germ cells.

Gene Pool

The collection of all alleles found in all of the individuals of a population.

Allele Frequency

The proportion of one allele, compared with all the alleles for that trait, in the gene pool.

Equation: Allele Frequency = Number of particular allele/ Total number of alleles.

Genetic Frequency

p = dominant

q = reccesive

p+q = 1

Hardy-Weinberg Equation

p²+2pq+q² = 1

What does it mean when the Hardy-Weinberg Equation is in equilibrium?

The population is stable and is NOT evolving.

Conditions for equilibrium within a population

There are no genetic mutations,

the population is very large

, there is no occurence of natural selection,

there is no introduction of new genetic material into the population,

individuals are equally likely to make with any other individual in the population.

Normal Distribution Graph

A normal distribution shows an arrangement of data in which most of the values fall in the middle of the data set, represented by the mean.

Stabilizing Selection

Intermediate phenotypes are selected over phenotypes at both extremes. Individuals that express the mean traits reproduce and and survive more effectively that individuals without these traits.

Directional Selection

This is the type of natural selection in which one extreme phenotype is selected over the other extreme phenotype and the average phenotype, shifting the mean toward one of the extremes.

Disruptive Selection

This is the type of natural selection in which both extreme phenotypes are favored, while individuals with the intermediate phenotype are selected against. Can lead to new species.

Gene Flow

The movement of genes into or out of a population and can cause a population to evolve.

Genetic Drift

Change in allele frequencies due to chance.

Bottleneck Effect in Genetic Diversity

Large amount of variety to a small amount of genetic variety due to a catastrophe.

Founder Effect

Genetic drift that occurs when a small number of indviduals become isolated from the orginal population and colonize a new area.

Sexual Selection

When females tend to select the strongest and optimal spouse to produce the best offspring with the strongest genes for survival and reproduction.

Intersexual Selection

Males displaying certain traits that attract femals.

When is a population in equilibrium?

Population is in equilibrium when genetic makeup does not change over time. Evolution Occurs.

Speciation

The rise of two or more species from a single existing species.

Species

Group of similar organisms that can breed and produce fertile offspring.

Reproductive Isolation

Occurs when two populations can no longer mate due to genetic differences

Physical Isolation

When two populations can no longer interact due to environmental factors that prevent contact.

Behavorial Isolation

Isolation caused by difference in courting and mating behaviors

Temporal Isolation

Inability to reproduce due to differing mating seasons

Adaptive Radiation

Large-Scale speciation through diversification of one common ancestor.

Stimulus

Something that triggers a response

Internal Stimuli

Any change in a organism’s internal environment that causes a response.

External Stimuli

Changes in external environment that causes a response.

Innate Behavior/Heritable Behaviors

Behaviors passed from generation to generation without it being taught.

How might migration become a innate trait?

Birds that migrate have a much higher likelihood to survive so natural selection selects for this beneficial trait so future generation behaviors match it. This overtime makes it become a trait that the entire population takes part in.

Survivorship

Number of individuals that survive over time

Communication

Sharing or exchanging information. Helps communicate with others, raise alarms in the presence of danger, helps attracts mates.

Mate Selection

Courtship displays help females choose which mate they should choose for the strongest offspring.

Defense

Responses to threatening stimuli from the environment. These behaviors help prevent death or injury on an individual or it’s species.

Reciprocity

Idea that sharing food will result in a future beneficial response such as being the recipient of shared food.

Kin Selection

Select for genes to help relatives

Altruism

Behavior in which an animal reduces its own fitness to help other members of its closely related social group.

Eusocial species

Organisms that have a job within a population but do not reproduce

Cultural Behavior

Behavior that is spread across a population largely through learning from others, rather than natural selection.