exam 3 Flashcards
What are monozygotic and dizygotic twins?
Monozygotic twins: developed from same zygote: share 100% of genes (identical twins). Dizygotic (fraternal) twins: two separate eggs fuse with different sperm cells (not identical; chance 1 in 80).
How many alleles are shared between each pair of twins, and you and your full sibling?
Monozygotic twins share 100% of genes, dizygotic twins share about 50% of genes. You share on average ~50% of your alleles with siblings.
What defines the function of a cell?
The function of a cell is defined by its genetic composition and the proteins it produces.
What is a mutation?
Mutation = change of base sequence; mutations can generate alleles and occur at random in different genes.
What are the four kinds of mutations?
The four kinds of mutations include point mutations, insertions, deletions, and duplications.
Which process can create a mutation?
During DNA replication, mistakes can happen.
What is the genotype?
Genotype is the genetic composition of an individual.
What is the phenotype?
Phenotype is the physical appearance of a trait.
What are recessive and dominant alleles?
Recessive alleles’ effects can only be seen if no dominant allele is present (lower case letters, rr). Dominant alleles’ effects can be seen even if one recessive allele is present (RR).
What is homozygous?
Homozygous means having the same alleles.
What is heterozygous?
Heterozygous means having two different alleles of a gene.
What are codominant alleles?
Codominant alleles: both alleles of a trait are fully expressed in heterozygous. The traits of both parents appear in offspring.
What is incomplete dominance?
Incomplete dominance: dominant allele in heterozygous is only partially expressed.
What is a monohybrid cross?
Parents differ in only one characteristic and only one gene is involved.
What is a Punnett square?
A Punnett square is a table that lists the different kinds of sperm and eggs the parents can produce in relation to their genes for a given trait.
What are the phenotype and genotype ratios for a monohybrid cross?
The phenotype ratio is 3:1 and the genotype ratio is 1:2:1.
What is a carrier?
A carrier is an individual who has one copy of a recessive allele that does not manifest in the phenotype.
What is the difference between quantitative and qualitative traits?
Quantitative traits cause continuous variation and result from multiple genes (polygenic traits). Qualitative traits show continuous variation due to both multiple genes and the environment.
What is phenotypic plasticity?
Phenotypic plasticity is the capability of each genotype to produce a range of phenotypes based on the environment.
What does ‘nature vs nurture’ mean?
NATURE is your genes, NURTURE is your environment.
What two factors affect the expression of a given trait?
The two factors are genetic makeup (nature) and environmental influences (nurture).
What is gene expression?
Gene expression is when instructions carried by genes are used to build proteins.
What are the similarities between DNA/RNA and proteins?
Both DNA (RNA) and proteins are polymers with a sequence of subunits (nucleotides/amino acids).
What defines the function and structure of protein?
Function and structure of protein is based on its amino acids and their sequence in the molecule.
What are the differences between DNA and RNA?
RNA has ribose instead of deoxyribose (sugar), RNA is single stranded, DNA is double stranded, and thymine is replaced by uracil in RNA.
What does transcription do?
Transcription rewrites DNA into RNA.
What is the main enzyme for transcription?
RNA polymerase is the enzyme that binds at the beginning of the gene on DNA (promoter region).
What does translation do?
Translation converts mRNA into a protein.
What are the main molecules involved in translation?
Ribosomes and transfer RNA (tRNA) are the main molecules involved in translation.
What is a codon?
A codon is a sequence of three nucleotides that codes for an amino acid.
What is an anticodon?
An anticodon specifies the amino acid that is carried by tRNA.
Where in the cell do transcription and translation take place?
Transcription occurs in the nucleus; translation occurs in the cytoplasm.
What is the genetic code?
The genetic code determines which mRNA codon corresponds to which amino acid.
What does redundancy of the genetic code mean?
The code is redundant: the same amino acid can be specified by different codons.
What does unambiguity of the genetic code mean?
The code is unambiguous: no codon codes for more than one amino acid.
What does universality of the genetic code mean?
The code is universal: all organisms use the same code to produce the same protein.
What are stem cells?
Stem cells are undifferentiated cells that can develop into different cell types.
What are genetically modified organisms?
Genetically modified organisms have genes from other organisms introduced or unwanted genes removed.
Humans descended from apes: TRUE/FALSE?
False; we share common ancestors.
Individuals can evolve during their lifetime: TRUE/FALSE?
False; it takes generations to evolve, and it’s a population that evolves, not an individual.
Evolution always takes thousands of years to change: TRUE/FALSE?
False; it does not take that long to change.
Evolution directs change towards a predetermined outcome: TRUE/FALSE?
False; your selection happens NOW.
You are related to some degree to planets: TRUE/FALSE?
True; we all have similar DNA.
What is a population?
Population: group of individuals of the same species that is separated by geography from other populations.
What does evolution mean?
Evolution: change in characteristics of a population that typically occurs over the course of generations.
What are microevolution and macroevolution?
Microevolution = changes that lead to different traits in a population over time. Macroevolution = changes that lead to new species over time.
What is the theory of common descent?
All species on earth are descendants of a single common ancestor.
What is evidence for a single origin of life?
All organisms share the same genetic code, DNA/RNA, and shared processes involved in gene expression.
What are homologies and homoplasies?
Homologies are traits inherited from a common ancestor; homoplasies are traits that arise independently.
What are vestigial traits?
Vestigial traits are remnants of biological heritage, indicators of common ancestry.
What are the 5 different lines of evidence for evolution?
The five lines of evidence include fossil records, comparative anatomy, molecular biology, biogeography, and embryology.
What are the 4 evolutionary forces?
The four evolutionary forces are natural selection, mutation, gene flow, and genetic drift.
What is natural selection?
Natural selection is the differential survival and reproduction of individuals in a population.
