Exam 1 Flashcards
unwinds and hold apart the replicating DNA.
helicase
stop the separated strands from rejoining
Binding protein
adds short primers to separate strands of DNA
primase
serve as anchors for construction of the new chains of DNA
primers
brings in nucleotides to bind to the exposed DNA strands, and it corrects errors made during replication
DNA polymerase
are also removed and replaced with the proper DNA bases
short primers
seals the sugar phosphate backbone of the DNA
ligase
The two strands of DNA are considered to be antiparallel
DNA directionality
what is the direction for DNA ?
5’ to 3’
a portion of the DNA code, a gene is a template for the synthesis of a complementary chunk of mRNA. mRNA carries codes specifying particular amino acids and directs protein synthesis.
transcription
What is being constructed in transcription?
mRNA
structure that is single stranded and instead of deoxyribose, has a slightly different sugar, called ribose
RNA
In RNA, the nitrogenous bases are what?
U instead of T
building blocks of proteins
amino acids
process of producing proteins is known as? usually makes ribosomes
translation
- initiate gene transcription at those regions
- ontain special sequences that signify the start point of particular gene
promoters
are non-protein- encoding fragments of genetic code
introns
are the portions of genetic code that ultimately get translated
exons
a change in the nitrogenous base sequence of a gene’s DNA
gene mutation
make up tissues and organs of the body ( 23 pairs of chromosome)
somatic cells
occurs in somatic cells typically during DNA replication so its very localized of the mutation
somatic mutations
any detectable and heritable variation in the lineage of germ cells
germline mutations
a change in a single DNA base
point mutation
- point mutation that changes a codon that normally specifies a particular amino acid into on that encodes for a different amino acid
- If the structured is changed results may be signs or symptoms of a disease or another observably different phenotype
missense mutation
point mutations that change a codon specifying an amino acid to “stop” codon. A stop shortens the protein product and can profoundly change its function
nonsense mutation
type of mutation that is responsible for addition or deletion of bases
formation shift mutation
What are the two types of formation shift mutation?
- insertion
2. deletion
areas that the sequence is repeated and the DNA may actually double up on itself
mutation hotspots
mutations that are caused by toxic exposures
induced mutations
an agent that induces a mutation
mutagens
wavelengths can damage DNA by causing an extra bond to form between pyrimidine bases located next to each other in a strand of DNA
UV radiation
a specific version of a gene; same from both parents homozygous and different heterozygous for that gene
alleles
the degree to which survival is helped or hindered by possession of a particular allele and its associated phenotype will determine the frequency of that allele within a population
natural selection
DNA is what type of material?
hereditary material
helical ladder shaped molecule that htas the capability of unraveling and making copies of itsel
DNA
DNA coils around proteins called what?
histones
the building blocks of DNA consist of nitrogenous bases that are bound to one sugar group and on phosphate groups
nucleotides
what are the 4 nitrogenous bases?
adenine (A), Guanine (G), thymine (T), and cytosine (C)
adenine and guanine are classified as what?
purines
thymine and cytosine are classified as what?
pyrimidines
what is the backbone of DNA?
sugar phosphate
what are the 4 types of changes in chromosome structure?
- deletion
- duplication
- inversion
- translocation
removes a chromosomal segment
deletion
repeats a segment
duplication
reverses a segment within a chromosome
inversion
moves a segment from one chromosome to another
translocation
- homologous pairs of chromosomes orient randomly at metaphase I meiosis
- each pair of chromosomes sorts maternal and paternal homologues into daughter cells independently of the other pairs
independent assortment of chromosomes
crossing over produces_____ which combine genes inherited from each parent
recombinant chromosomes
adds to genetic variation because any sperm can fuse with any ovum
random fertilization
what are the three mechanisms for genetic variation
- independent assortment of chromosomes
- crossing over
- random fertilization
results in accumulation of genetic variations favored by the environment
natural selection
large-scale chromosomal alterations leads to what?
spontaneous abortions or miscarriages or cause a variety of developmental orders
pairs of homologous chromosomes do not separate normally during meiosis
nondisjunction
results from fertilization of gametes in which nondisjunction occured
aneuploidy
a zygote has only one copy of a particular chromosome
monosomic
zygote has three copies of a particular chromosome
trisomic
a condition in which an organism has more than two complete sets of chromosomes
polyploidy
is polyploidy common in plants or animals?
plants
are polyploidy more normal in appearance than aneuploidy?
yes
an aneuploid condition that results from three copies of chromosome 21
down syndrome
the result of an extra chromosome in a MALE, producing XXY individuals
Klinefelter syndrome
produces X0 females, who are sterile; it is the only known viable monosomy in humans
Turner syndrome
- results from a specific deletion in chromosome 5
- delayed development
- small head size
- low birth weight
- weak muscle tone in infancy
cri du chat
type of allele that determines the organism’s appearance
dominant allele
type of allele that has no noticeable effect on appearance
recessive allele
states that 2 alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes
law of segregation
diagram for predicting the results of a genetic cross between individuals of known genetic makeup
Punnett square
what are the 3 degrees of dominance?
- complete dominance
- incomplete dominance
- codominance
occurs when phenotypes of the heterozygote and dominant homozygote are IDENTICAL
complete dominance
the phenotype of hybrids is SOMEWHERE BETWEEN the phenotypes of the two parental varieties
incomplete dominance
2 dominant alleles afeect the phenotype in separate, distinguishable ways
codominance
the property that most genes have multiple PHENOTYPIC effects
pleiotrophy
gene at one locus alters the phenotypic expression of a gene at a second locus
epistasis
characters that vary in the population along a continuum
quantitative character
an additive effect of 2 or more genes on a single phenotype
polygenic inheritance
what is an example of a polygenic inheritance?
skin color in humans
the phenotypic range of a genotype influenced by the environment
norm of reaction
term that describes genetic and environmental factors as something that influences phenotype
multifactoral
what are examples of multifactorial disorders?
- CVD
- cancer
a family tree that describes the interrelationships of parents and children across generation
pedigree
true or false. many genetic disorders are inherited in a recessive manner
true
are HETEROZYGOUS individuals who carry the recessive allele but are phenotypically normal
carriers
a recessive condition characterized by a lack of pigmentation of skin and hair
albinism
a form of dwarfism caused by a rare DOMINANT allele
achondroplasia
gene located on either sex chromosome
sex-linked gene
sex linked recessive disorders are more common in males or females?
males
phenotype depends on which PARENT passed along the alleles for mammalian traits
genomic imprinting
the liquid that bathes the fetus is removed and tested
amniocentesis
sample of placenta is removed and tested
chorionic villus sampling (CVS)
the process of helping people understand and adapt to the medical, psychological and familial implications of genetic contributions to disease
genetic counseling
the process by which DNA directs protein synthesis, includes two stages
transcription and translation
who developed the one gene to one enzyme hypothesis that states that each gene dictates production of a specific enzyme?
Beadle and Tatum
the synthesis of RNA under the direction of DNA?
transcription
transcription produces what?
mRNA
