Final Exam part 1 Flashcards
What is the nature of science?
to ask questions that can be answered by observing or measuring things
What are the dependent and independent variable on a graph?
independent- x-axis
dependent- y-axis
what are the steps of the scientific method?
observation/question, research topic area, hypothesis, test with an experiment, analyze data, report conclusions, repeat…
What is a hypothesis?
a proposed explanation based on limited evidence and used as the starting point for developing an experiment. Should be precise and testable
What is a null hypothesis and what is its purpose?
It states that the hypothesis is not the explanation. It makes the scientist be able to see if the data collected was by random chance or not
What is the control of an experiment?
It is the basis for which comparisons are made during an experiment, the group left unchanged.
What is DNA?
Deoxyribonucleic acid
What stores the genetic information in cells?
DNA
What is a nucleic acid?
a polymer made up of monomers called nucleotides
What was the Hershey-Chase experiment?
An experiment that determined that DNA stores genetic material, not proteins as previously thought
What do T2 proteins contain (used in the Hershey-Chase experiment)?
sulfur
What does DNA contain (used in the Hershey-chase experiment)?
phosphorous
What is a polymer?
a substance consisting of repeating subunits (monomers)
What is a nucleotide?
a phosphate group bonded to a 5carbon sugar which is bonded to a nitrogenous base
What are the single-ring nitrogenous bases?
cytosine, uracil, and thymine
What are the double-ringed nitrogenous bases?
guanine and adenine
What is the primary structure of DNA?
a directional sugar-phosphate backbone
What is the secondary structure of DNA?
an anti-parallel double helix
What was the Watson & Crick experiment?
discovered the sugar-phosphate backbone of DNA, and discovered the rules of nitrogenous base pairings
What did Rosalind Franklin and Maurice Wilkins do?
Used x-ray crystallography to determine that DNA has a helical shape
What is complementary base pairing?
adenine to thymine, guanine to cytosine
Where is DNA found in eukaryotes?
chromosomes
What is DNA replication?
Using the genetic code of DNA to synthesize new DNA
DNA replication is ______
semi-conservative
What is meant by DNA replication is semi-conservative?
parental strands separate, and each are used as a template strand for a new daughter strand
What are the steps of DNA replication?
- replication bubble forms at the origin of replication
- DNA synthesis proceeds in the 5’ to 3’ direction, adding nucleotides at the 3’ end
- Active DNA synthesis takes place at the replication forks of the bubble
- synthesis occurs on both strands of the template DNA at the replication forks
What direction does DNA synthesis occur in the leading strand?
5’ to 3’ or towards the replication fork
What direction does DNA synthesis occur in the lagging strand?
3’ to 5’ or away from the replication fork
What is the central dogma?
DNA (transcription) mRNA (translation) proteins
What happens during transcription?
RNA polymerase uses a template DNA strand to a complementary nucleotide to the growing mRNA strand in the 5’ to 3’ direction (adds to the 3’ end)
Is mRNA single or double stranded?
single
What is translation?
The use of mRNA as a genetic code to produce protein
What is the genetic code?
The coding for amino acids produced when 3 base pair triplets are read
What are codons?
3 base pair triplets
What is the start codon?
AUG
What are the features of the genetic code?
It is redundant, unambiguous, non-overlapping, (nearly) universal, and conservative
What is a gene?
A section of DNA which codes for a protein
What are chromosomes?
Organized DNA that are made of a single long DNA double helix wrapped around histone proteins
What is a chromatin?
Complex of DNA which codes for a protein
What is a locus?
The physical location of a gene on a chromosome
What is an unreplicated chromosome?
A single, long DNA double helix wrapped around histone proteins
What is a replicated chromosome?
Consists of two copies of the same DNA double helix
What is a diploid cell?
A cell containing two sets of chromosomes
What is a haploid cell?
A cell containing one set of chromosomes
What are alleles?
Different versions of the same gene
What is gene expression?
Set of processes that converts the information in DNA into the product of a gene
What is a genotype?
The alleles of a gene present within a single organism
What is the one gene - one polypeptide hypothesis?
each gene contains information to produce one protein
What is a phenotype?
A detectable trait of an organism
What is an important exception to the central dogma?
Many genes code for RNA’s that function directly in the cell
What does heterozygous mean?
Containing two different alleles of the same gene
What does homozygous mean?
Containing two of the same alleles of the same gene
What is a dominant allele?
When the phenotypic effect can be seen anytime the allele is present
What is a recessive allele?
The phenotypic effect can only be seen in homozygous individuals
What is a mutation?
Any permanent change in an organism’s DNA
What is a point mutation?
A mutation that alters the sequence of one or a small number of base pairs
What is a silent mutation?
Change in the nucleotide sequence that does not alter the amino acid specified
What is a missense mutation?
A change in the nucleotide sequence that does alter the amino acid specified by the codon (can be beneficial, deleterious, or neutral)
What is a nonsense mutation?
A change in amino acid sequence that results in an early stop codon (AUG)
What is a frameshift mutation?
The addition or deletion of a nucleotide (almost always deleterious)
What is chromosome mutation?
A larger scale mutation that changes either the structure or the number of chromosomes
What is a deletion?
When broken segments of a chromosome get lost
What is an inversion?
When broken chromosomes are flip and rejoined
What is duplication (chromosome mutation)?
One or more additional copies of a segment
What is translocation?
When a broken piece becomes attached to a different chromosome
What is the blending inheritance hypothesis?
Traits of a mother and father blend together to form offspring
What are pure-breeding lines?
Lines that produce offspring identical to the parents
What are hybrids?
Offspring from matings of two true breeding parents that differ in one or more trait
What is a monohybrid cross?
Breeding between pure-breeding lines that are homozygous for different alleles of the same trait
What is the particulate inheritance hypothesis?
Hereditary determinants are discrete and maintain their integrity from one generation to the next
What is the principle of segregation?
Two members of each gene must segregate into different gametes
What is independent assortment?
Alleles of different genes do not stay together when gametes form
What are the traits of homologous chromosomes?
Same size and shape, contains the same genes at the same loci, and the DNA sequence is not identical
Are gametes haploid or diploid?
Haploid
What happens during meiosis I?
Cells replicate each of their chromosomes into sister chromatids. Then homologous chromosome are separated into daughter cells
What happens during meiosis II?
Sister chromatids separate and become individual chromosomes. The daughter cell now has a copy of each chromosome
Independent assortment of chromosomes into gametes creates _______.
New combinations of alleles
What does crossing over do?
Produces new populations of alleles within a chromosome
What is a population?
A group of individuals within a species living in the same space or geographic areas
What can be studied about populations?
- How populations change over time in size and in trait frequencies
- How populations of the same species in different locations vary
- How individuals within one population may vary
- How the environment influences the population
There is variation among individuals in almost all populations. What kind?
phenotypic, genotypic, and allele
Where does variation come from?
Mutations, crossing over, genetic recombination into gametes, and random fertilization
What is a gene pool?
All alleles present within a population
What are gene pools characterized by?
Genotypic frequencies and allele frequencies
What does Hardy-Weinberg state?
Within a population, if:
1. The population is infinitely large,
2. Mating is random
3. There is no natural selection
4. No mutations occur
5. No migration occurs
Then the trait under study will be in Hardy-Weinberg Equilibrium
What is the equation for Hardy-Weinberg Equilibrium?
p^2 + 2pq + q^2 = 1
What is evolution?
The change in allele frequencies in a population over time (occurs when a population is not in Hardy-Weinberg Equilibrium)
What are the four mechanisms of evolution?
- mutation (weak force)
- gene flow (strength depends on degree of movement)
- genetic drift ( strong effect on small populations)
- Natural selection (most powerful force)
What is gene flow?
When an individual or gametes move between populations
What is genetic drift?
When chance events determine which alleles are passed to the next generation
What is the bottleneck effect?
large -> small -> large, usually occurs when a natural disaster wipes out a large amount of a population
What is the founders effect?
When a few individuals isolate from a large population and form a new population, resulting in a random subject of new allele within the new population
What is positive assortative mating?
When similar genotypes are more likely to mate than dissimilar ones (increases homozygosity)
What is negative assortative mating?
When dissimilar genotypes are more likely to mate than similar ones (increases heterozygosity)
What is inbreeding?
Mating between related individuals (increases homozygosity)
What is an inbreeding depression?
When related individuals mate causing a decrease in survival and fertility of offspring
What was Plato’s “perfect essence”?
Claimed that every organism was an example of a perfect essence, created by god and that type was unchanging
What is typological thinking?
Classifies things only in terms of the types they belong to and view variation as abnormal
What was Aristotle’s “great chain of being”?
Species were fixed types organized into a sequence based on size and increasing complexity.
What was the law (theory) of use and disuse?
The more an organ is used, the larger and stronger it gets. The less it is used, the more the organ deteriorates
Who created the law of use and disuse and the law of inheritance of acquired characteristics ?
Jean-Baptiste Lamarck
What was the law (theory) of inheritance of acquired characteristics?
All the losses or acquisitions shaped by nature on an individual are preserved by the reproduction of new individuals
Who was Charles Darwin?
Described variation among individuals within a population, and across closely related species
What is natural selection?
A process through which certain characteristics survive and reproduce at a higher rate because of those characteristics
What does natural selection lead to?
adaptations
Natural selection is a major force for driving what?
allele frequency change
Natural selection is the chief mechanism for ______.
transforming populations
What is fitness?
The ability of an organism to survive and reproduce compared to other individuals of a populations
What are the requirements of the theory of evolution by natural selection?
- Variation
- Inheritance
- Struggle for existence
- Differential survival and reproduction
What is an adaptation?
A characteristic of an organism that improves fitness within its environment
What are the types of natural selection?
directional selection, stabilizing selection, and disruptive selection
What is directional selection?
Individuals at one phenotypic extreme are favored
What is stabilizing selection?
Individuals with an intermediate phenotype are favored
What is disruptive selection?
Individuals at both phenotypic extremes are favored
How do we determine if natural selection is occurring within a population?
We have to determine if the trait arising is increasing an individual’s fitness
What measures can we use to quantify fitness?
direct and indirect measures
What is a direct measure?
survival rates and number of offspring
What are some indirect measures?
Health, body size, etc…
What are common misconceptions about natural selection?
- Natural selection changes individuals
- Natural selection is goal oriented
- Natural selection leads to perfection
- natural selection is the only process of evolution
What is sexual selection?
Selection because of preference by one sex for certain characteristics of individuals of another sex
What is intersexual selection?
Selection because of characteristics (non-random) called mate choice
What is intrasexual selection?
Selection through competition (non-random).
What can intersexual selection cause?
sexual dimorphism
What is the Bateman-Trivers Hypothesis?
Production of eggs is more costly than the production of sperm, so females should be choosy and protect themselves.
What are honest signals?
Traits that signal health and quality
Sexual selection and natural selection can conflict such that ______________.
traits preferred in mating decrease survival
Mutations are random in regards to __________.
The phenotypes they produce
Natural selection acts upon _________.
existing variation
New traits evolve from ________.
ancestral traits
If mutation is favorable by chance, it may _____ the population due to ______________.
increase, increased fitness of the organism
Does assortative mating influence genotype frequency or allele frequency?
genotype frequency
