Quiz 1 Flashcards
genetic code
is the correspondence between mRNA codons and the 20 amino acids of life. It enables cells to construct proteins using DNA instructions that have been transcribed into RNA.
Alternate splicing
cuts mRNA in different ways, forming slightly different combinations of exons for some genes.
Introns
are sequences that are transcribed but then cut themselves out before exiting the nucleus. The protein-encoding exons of the mRNA join and are proofread.
Transcription factors
are proteins that control which genes are transcribed in a cell under certain conditions by binding DNA in response to signals from outside the cell.
DNA replication is semiconservative
in that the two parental strands separate and each is a template for assembling new daughter strands. Semiconservative means that each new DNA double helix conserves half of the parental one.
complementary base pairs
with T and G with C. Hydrogen bonds hold the base pairs together.
antiparallelism
The two polynucleotide chains run head-to-toe, based on the relative locations of the carbons in the sugars (5’ to 3’ and 3’ to 5’).
nucleotide
A building block of DNA, which consists of one deoxyribose, one phosphate group, and one nitrogenous base.
purine bases
adenine and guanine
pyrimidine bases
cytosine and thymine
gene pool
refers to all the alleles of a given population
Pedigrees
are diagrams that depict the transmission of recessive and dominant traits through generations.
Dominant alleles
are expressed when one copy is present
Recessive alleles
require two copies for expression.
genotype
is the allelic makeup of an individual
phenotype
is the observable or measurable expression of an individual’s alleles (traits or health condition).
stem cells
that “self-renew” as well as produce cells that specialize. These two properties are essential for growth, development, and healing.
Mendelian trait
cause by a single gene
multifactorial trait
is caused by one or more genes and environmental influences. Most genes do not function alone.
karyotype
is a chart of an individual’s chromosomes.
somatic cell
23 pairs of chromosomes, constituting two copies of the genome. Twenty-two pairs are autosomes and do not differ between the sexes, and one pair is the sex chromosomes. XX is female; XY is male.
Chromosomes
consist of hundreds of genes
alleles
arise by mutation, which can cause disease. A mutation also refers to a change in a gene.
nitrogenous base pairs
adenine and thymine
guanine and cytosine
