unit 5 Flashcards
sexual reproduction
promotes genetic variation
2N= diploid
chromosomes in homologous pairs
humans have 2N
46 chromosomes, 23 homologous pairs
homologous pairs
chromosomes that carry info about same characteristics
how many autosomes
22 pairs
how many sex chromosomes
1 pair, xx-female xy-male
n= haploid
1 member of each homologous pair
meiosis
mitoic division
separation of homologous pairs
2nd miotic division (separation of sister chromatids)
trisomy 21
down syndrome
karyotype
display of chromosomes in pairs
miosis 1
prophase I: homologous pais come together to form Tetrads crossing occurs (exchange of genes between homologous pairs)
Metaphase I: homologous pairs line up along metaphase plate
anaphase I: homologous pairs separate and move to opposite side of cells
chiasma
location where crossover occurs in prophase 1 of miosis
Meiosis I
prohase II
metaphase II: sister chromatids line up along metaphase plate
anaphase II: sister chromatids move to opposite sides of cell
telophase: haploid daughter cell forms.
genetics
science of heredity
gregor mendel
father of science of genetics
phenotype
physical characteristics expressed
genotype
genetic information
alleles
contrasting genes for same characteristics
genetic variation
sexual: crossing over, independent assortment of chromosome pairs, random fertilization
asexual: mutation
Law of segregation
homologous pairs will separate during mitosis
law of independent assortment
homologous pairs line up independently of one another at metaphase I
incomplete dominance
neither allele is dominant to the other
multiple alleles
3 or more contrasting genes for the same characteristics
epistasis
one gene influences the phenotypic expression of another
polygenic inheritance
several to many genes collectively produce genotype
pedigree analysis
a family history over several to many generations
test cross
genetics cross used to determine an unknown genotype
fetal testing: amniocentesis
14-16th week of pregnancy body cells in fluid > extracted> fetal cells> karyotype
fetal testing: CVS
vacuums cells out of fetus ands tests is (faster and riskier)
carrier recognition
determines if person is a carrier of specific genetic disorder
newborn screening
PKU
gene
unit of hereditary info on a chromosome
sequence of nucleotides which code for a polypeptide
mutation
any change in sequence of DNA nucleotides (natural or induced)
chromosome maps
display linear order of genes on a chromosome
linked genes
genes found on same chromosome
linkage maps
based upon rates of crossing over
1% crossing over=1 map units of distance of chromosome
sex-linked genes
genes found on x or y sex chromosomes
duchennes muscular dystrophy
unable to produce muscle contracting protein
barr body
inactive x chromosome
aneuploidy
a chromosome # higher or lower than diploid
nondisjuction
failure of a homologous pair of sister chromatids to separate during meiosis
turner syndrome
45 chromosome XO female sterile
shorter then average, reprodutive system not properly developed
kleinfelter syndrome
47 chromosome XXY male sterile
low levels of testosterone, underdeveloped
deletion
the loss of one or more genes on a chromosome
inversion
change in linear order of genes
translocation
exchange of genes between non homologous chromosomes
cri du chat
deletion of chromosome #5 mental disorder
extra nuclear genes: mitochondria:
inability to produce ATP in adequate amounts
extra nuclear genes: chloroplast
genes can code for specific plant pigments
chromosomes
composed of DNA and proteins
nucleotides
building blocks of DNA
- nitrogen base
- 5 carbon sugar
- phosphate grouo
fragments:
group of lagging strands (away from fork) also known as Okazaki fragments
leading strand
formed continuously (towards the fork)
RNA primer
several strands of RNA added to the lagging strand, it begins the synthesis of the lagging strand in DNA replication
DNA polymerase
connects DNA nucleotide in the 5’ to 3’ direction
telamiere
repetitive sequence of DNA nucleotide which does not code for protein
albanism
individual does not produce melanin protein pigment
cystic fibrosis
excess build up of mucus on the lining of the lungs and other internal organs
sickle cell disease
abnormal hemoglobin
pku
excess phenylamine in blood, causes mental retardation
tay-sachs disease
excess amount of lipids in brain tissue
anchondrosplasia
form of dwarfism
huntigtons disease
generative disease of the nervous system, affect individual in midlife
RNA
single stranded
ribose
uracil
mRNA
formed on DNA surface
carries code for polypeptide from nucleus to the surface of the small ribosomal subunit
CODONS
the nitrogen bases in mRNA are read in groups of 3 nucleotides
tRNA
65-75 nucleotides
found in cytoplasm
attaches to specific amino acid and carries it to surface of the large ribosomal subunit
ACC
attachments site for amino acid
Function of RNA polymerase
unzips DNA and assembles RNA nucleotide in the 5’ to 3’ direction
exon
coding nucleiotides
intron
non coding nucleotides
splicesosomes
removes intron and splices together exons
Operon System: PROMOTER
- sequence of nucleotides to which RNA polymerase attaches
Operon System: OPERATOR
- sequence of DNA nucleotides which acts like a switch, if switch is ON synthesis of polypeptide occurs
Operon System: GENE
- a gene(s) which code for polypeptide
regulatory gene
sequence for DNA nucleotide which code for repressor protein
active repressor
binds to operator and turns it off
DNA ligase
enzyme that in the cell repairs single-stranded discontinuities in double stranded DNA molecules
transcription
DNA to pre-mRNA
translation
tRNA to polypeptide
