Exam 3 (Basic concepts) Modules 9-12 Flashcards
What is DNA?
A long molecule composed of nucleotides that contains genetic instructions and information.
What three components make up a nucleotide?
A phosphate, a sugar (deoxyribose), and a base.
What are the four nucleotides in DNA?
Adenine (A), Cytosine (C), Thymine (T), Guanine (G).
What does Adenine pair up with?
Adenine can only pair up with Thymine.
What does Cytosine pair with?
Cytosine can only pair with Guanine.
What are the four functions of DNA?
Store genetic information
Copy or replicate genetic information (to pass down future cells?
Express information
Occasionally mutate (change information)
DNA replication
The duplication of two identical replicas of DNA information
What is the job of enzymes?
The job of the enzyme is to unzip the double helix
Which strand contains the information for DNA construction?
Since both strands are complimentary, both strands contain the information.
How are errors limited?
Errors are proofread by enzymes.
What does an organisms genome determine?
Genomes determine Phenotype.
What is phenotype?
The physical characteristics of an organism.
What are genes expressed by?
Transcription and translation.
What is transcription?
Is when the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA). DNA to RNA.
What is translation?
mRNA is decoded to build a protein that contains a specific amount of amino acids. RNA to protein.
What controls the expression of genes?
Chemical signals (hormones, etc)
What is DNA used for in transcription?
Template to construct an RNA molecule.
What is RNA?
RiboNucleic Acid chain composed of 4 nucleotides.
How does RNA differ from DNA?
- Includes the sugar ribose (not deoxyribose).
- Uracil (U) instead of Thymine (T)
- RNA is usually a single strand and not a double helix.
What does RNA polymerase do?
Unwinds DNA and transcribes one complimentary strand into RNA.
In RNA what does Adenine pair with?
Adenine pairs with Uracil (U).
In RNA what does Cytosine pair with?
Cytosine pairs with Guanine.
Does mRNA stay in the nucleus?
No, mRNA leaves the nucleus.
What does codon do?
Codes for one amino acid.
What structure performs translations?
Ribosomes.
What does tRNA do?
transfer RNA carries a specific amino acid to the ribosome.
Who is Gregor Mendel?
1822-1884, Augustarian monk in the Austrian Empire (Now Czech Republic).
Why were pea plants ideal?
Discrete traits (flower color, seed shape, plant height, etc), can be hand pollinated, and grow quickly.
What was the first cross Mendel did?
Yellow pea with a green pea, which resulted in the F1 generation being all yellow.
What is F1?
First filial generation produced by the parents.
What is F2?
Second filial is the offspring from F1 to interbreed.
What did Mendel deduce?
Individuals have 2 (factors) for each trait (alleles)
What is an allele?
Variant form of a gene.
What is a Punnet square?
Method to predict the outcome of offspring.
What is a dihybrid cross used for?
Look at two traits simultaneously.
What is the law of Independent assortment?
Allele pairs separate during the formation of gametes, meaning that traits are transmitted to offspring separately.
What happens to chromosomes if they are close together?
They become linked.
What is the result of incomplete dominance?
Intermediate phenotypes in heterozygotes.
When was natural selection publicly proposed?
1858
What four principles did Darwin’s concept of natural selection combine?
Overproduction (reproduction more than replacement)
competition for resources limits the size of population
differential survival and reproduction (survival of the fittest)
Inheritance and accumulation of favorable variations
What causes different fitness levels among individuals?
Interaction between environmental conditions and traits
How does fitness increase overtime?
Natural selection.
Convergent evolution
process whereby organisms not closely related (not monophyletic), independently evolve similar traits as a result of having to adapt to similar environments
How does artificial selection differ from natural selection?
the selection occurs as a result of human choice/interaction.
What is needed for evolution to occur?
Mutation
Immigration/ gene flow
Natural selection
Genetic drift
Where do new alleles come from?
Mutation
Immigration/ gene flow
Imports alleles from other populations
What helps maintain genetic diversity?
Mutation and Immigration/ gene flow.
Mutations
the physical changes in a nucleotide sequence.
What has the potential to increase mutation rate?
Stress (mutation not a guarantee to adapt to environmental changes.
What are the reasons for mutations?
DNA sequence may be copied incorrectly during DNA replication.
Chromosomes may be “matched up” incorrectly during crossover in meiosis.
What does immigration/gene flow maintain?
Genetic diversity and genetic similarity between different populations.
What affects allele frequency in a population due to change though time?
Natural selection and genetic drift.
What does natural selection depend on?
The fitness of alleles in a particular environment, the alleles favored may differ under different circumstances.
What is selective pressure?
Can be abiotic or biotic but is the phenomena that alters the behavior or fitness of a living organism.
What does a stronger selective pressure mean?
Faster change in allele frequency,
What does it mean when an allele is at a disadvantage?
There is selective pressure against them.
What can be included in selective pressure?
Nutrient availability and herbivory.
What is competition?
The competition of resources (like water, space, light) which leads to faster growth, chemical weapons and efficient roots.
What is genetic drift?
Changes in allele, frequency that is random with respect to fitness.
Why are some alleles lost?
Genetic drift (which is not adaptive).
What happens to alleles that are more frequent due to genetic drift?
Aren’t guaranteed to increase fitness.
What is a species?
a group of individuals that may potentially interbreed in nature and defines species as groups that have low potential to reproduce with each other.
How to get a new species?
2 populations become different enough to be considered different species when they go through mutation, immigration/gene flow, natural selection and genetic drift.
Allopatric speciation
geographic isolation of populations which causes reproductive isolation and can result in the accumulation of differences large enough for population to eventually be different species.
Sympatric speciation
the evolution of a new species from an ancestral species that both continue to inhabit the same geographic region.