Test 4 Flashcards
genotype
the genetic make up of an organism
phenotype
the observable physical characteristic
gene
section of DNA that codes fro a specific protein product or RNA molecule
transcription
the process of RNA synthesis from a DNA template
mRNA
an RNA molecule made as a complementary copy of a gene formed as a single strand by a mechanism similar to DNA replication
RNA polymerase
the enzyme responsible for attaching RNA nucleotides together in the sequences specified by the DNA
introns
segments/sequences not specifically involved in coding for a polypeptide
Exons
segments/sequences that are placed together to form the final mRNA molecule to be used by a cell
translation
the nucleotide sequences of mRNA is used to determine the amino acid sequence
codon
every set ig 3 bases in the mRNA molecule
genetic code
consists of 64 possible codons, 61 of which code for amino acid
genetic engineering
the insertion of DNA from one species into another to allow donor DNA sequences to be expressed by the recipients
rRNA
produced in the nucleus by transcription, and it joins with proteins to form the subunits of ribosomes.
tRNA
produced in the nucleus by transcription, and it transports specific amino acids to a ribosomes to align them correctly to form a new polypeptide chain
anticodon
a series of three bases on a tRNA molecule that will pair with the complementary codon on an mRNA molecule
what is the DNA template used for?
to generate molecules that will be used as working copies to be read in the making of new protein molecules
What “start signal” (in the DNA template) does an RNA polymerase enzyme use in order to know where to start in transcribing (creating) a new mRNA molecule?
AUG
What could happen to an mRNA molecule that is sent out into the cytoplasm without a 5’ cap and a poly(A) tail?
(It could broken down by cell enzymes (after being perceived as an “purposeless” molecule, and a ribosome might also have difficulty attaching to it.)
Where in a eukaryotic cell can translation occur?
transcription occurs in the nucleus and translation occurs at ribosomes in the cytoplasm
Why is the genetic code described as redundant, and how does that ensure that many “third letter” codon mutations will be silent?
there are often 2 or more codons with different third bases that “code for” the same amino acid
How does the universality of the genetic code make genetic engineering possible?
all genetic code is the same amongst all living organisms
What signal allows the process of translation to come to an end?
UAA, UGA, UAG
Are mutations always detrimental?
No –they can sometimes confer beneficial characteristics on an organism, and provide the “raw material” for evolution to occur!
What amino acid corresponds to the “start codon” carried by every mRNA molecule?
AUG
point mutation
change in one base pair of a gene
silent mutation
mutations that are not evident in an organisms phenotype due to the fact that the letter sequence change
missense mutations
switch an amino acid codon into a codon for a different amino aid giving the protein different functional characteristics
nonsense mutations
switch an amino acid codon into a stop codon
insertion mutation
addition of nucleotide pairs in a gene
deletion
removal of nucleotide pairs in a gene
frameshift mutation
alteration in the way that all “downstream” codons will be read
spontaneous mutations
mutations can occur naturally due to errors made during DNA replication, DNA repair, or DNA recombination
mutagens
chemical or physical agents that interact with DNA to cause mutation
How do insertion and deletion mutations cause frameshift mutations? Why would frameshift mutations be very unlikely to be “silent?”
because the insertion of an amino acid would cause the rest of the amino acids to change. the change would likely cause a silent mutation because many of the amino acids make the same codon
Will all mutations be passed on?
no
What kinds of conditions can cause a point mutation to also be a silent mutation?
When the amino acid changes but doesn’t change the outcome
evolution
refers to the changes in the genetic makeup go in biological populations over time
population
group of individuals of a single species that live and interbreed in a particular geographical area
microevolution
changes in the genetic makeup of populations
macroevolution
large-scale evolutionary changes that can lead to speciation
natural selection
differential survival and reproduction between individuals within a population
artificial selection
the selective breeding of organisms by humans to emphasize preferred characteristics of offspring
mutation
any change in the nucleotide sequence of an organisms DNA
adaptation
a trait that is favored by natural selection
species
a group. of populations whose individuals have the potential to interbreed and produce fertile offspring under natural conditions
gene pool
total aggregate of genes in a population at any given time
fixed allele
when all the members of a population only contain one type of allele for a given trait
Hardy-Weinburg equilibrium
must satisfy the five conditions of evolution
sexual selection
nonrandom mating in which an organisms phenotype impacts its ability to attract mates
genetic drift
a phenomenon that can occur in a small populations when random chance events impact allele frequencies
bottleneck effect
occurs when a number of individuals in a population are removed from the gene pool due to environmental disaster
founder effect
occurs when a new population is established by a few individuals with limited genetic variety
gene flow
interbreeding via genetic change between populations
How likely is it that all of the requirements for Hardy-Weinberg equilibrium will actually be met in populations in the wild?
very low
Why are small populations more prone to the effects of genetic drift
(By their nature, small populations will contain less genetic diversity than larger populations, and that genetic diversity will be harder to “maintain” due to chance/random events that may occur.)
On what continent did Darwin first gather many of the examples that he would later use in forming his theory of evolution by means of natural selection?
South America
What scientist was a contemporary of Darwin’s who independently came to a similar understanding of evolutionary theory (causing them to present their ideas jointly)?
Alfred Russel Wallace
Did Darwin have a good understanding of the genetics underlying evolutionary change? Why or why not?
No genetic evidence was available at the time he took his first voyage, so he had no knowledge
What are the main inferences/tenets underlying Darwin’s concept of evolution via natural selection
overproduction, inheritance/competition, and natural selection.
Is artificial selection likely to produce the same outcomes that natural selection would? Why or why not?
Not necessarily. If the outcome is favorable for humans, then it likely would, but if it is unfavorable, then the outcomes would be different
What produces the genetic variation between individuals that natural selection will act upon?
mutations
Do all mutations have negative impacts on an individual?
no
Will an adaptation that helps an organism to survive and reproduce in one environment cause it to be equally successful across all other environments? Why or why not?
no, adaptation helps the organism survive BASED on its environment, so different environments will required different adaptations
Can an individual organism undergo evolutionary change to better suit its environmental conditions? Why or why not?
no, adaptation occurs on a population level, not an individual level
Does the Hardy-Weinberg principle best describe evolving or nonevolving populations?
non evolving
what are the five conditions that must be met in order for Hardy-Weinberg equilibrium to be present:
no mutations, random mating, no natural selection, a large population size, and no gene flow into/out of the population.
In the Hardy-Weinberg equation, p2 + 2pq + q2= 1.0, what does the “p” stand for?
The dominant allele (A)
In the Hardy-Weinberg equation, p2 + 2pq + q2= 1.0, what does the “q” stand for?
the frequency of the recessive allele (a)
What is the single advantage of sexual reproduction over asexual reproduction?
increased genetic variety
While new alleles arise within populations due to mutation, does every mutation produce a new allele?
No, some mutations are silent and therefore cause no change
Darwinian Fitness
the contribution that an individual makes to the gene pool of the next generation
relative fitness
the contribution of one specific genotype to the next generation
directional selection
occurs when one phenotype extremes are favored over an intermediate phenotype
diversifying selection
occurs when one phenotypic extreme of the other is favored over any intermediate phenotype
stabilizing selection
occurs when an intermediate phenotype is favored over any extreme phenotype
Why are evolutionary processes more “observable” in species with short generation times?
because most mutations occur over multiple lifetimes while these mutations can occur when the human lifetime
What are the limitations on natural selection
(1)evolutionary change must work with pre-existing structures and cannot “start from scratch”
(2) adaptations are often compromises and are rarely perfect solutions
(3) random events and genetic drift can lead evolution in a direction that is not truly adaptive
(4)natural selection can only act on the genetic diversity currently present in a population.
mitosis
asexual cell division to produce clonal cell s
asexual reproduction
reproduction that involves one parent and occurs without the fusion of gametes
clone
genetically identical to the parent
chromosomes
made of DNA tightly wound around histone proteins
chromatin
unwind DNA that is loosely looped around histone proteins
interphase
a metabolically active stage that alternates with mitosis
g1 phase
centered on intense biochemical and growth activity
S phase
involves DNA replication
sister chromatids
identical copies of a DNA molecule that are held together at their centers
g2 phase
centered on protein synthesis and completing final preparations for cell division
prophase
Chromatin thickens (condenses) into chromosomes
Telophase
Chromosomes de-condense
Nuclear membranes reappear around each set of copies
This creates two distinct nuclei in the same cell
Spindle fibers completely disappear
cytokinesis
division of the cytoplasm creating two new cells, follows mitosis
sexual reproduction
happened when haploid male and female gametes fuse to produce a diploid zygote
gametes
haploid sex cells
zygote
a diploid cell created from two haploid cells that will develop into genetically unique individual
haploid
posessing one set of chromosomes
diploid
processing two sets of chromosomes
homologous chromosomes
pair of chromosomes that code for the same informations, with one of each pair obtains from one parents and from the other
meiosis
the process that reduces chromosome number from the diploid to haploid in those cells that can participate in sexual reproduction
crossing over
gene swapping
What are the products of asexual reproduction (mitosis)?
2 haploid daughter cells
What would be an advantage and a disadvantage of asexual reproduction?
advantage: there is no time wasted by finding a mate
disadvantage: Because offspring are identical none of them will be any better adapted to their environment.
What stages comprise interphase?
G1 phase (cell growth), followed by S phase (DNA synthesis), followed by G2 phase (cell growth).
What are the products of sexual cell reproduction
a zygote
