female somatic cells have
14 chromosomes
males somatic cells have
13 chromosomes
klinefelter syndrome
individuals have more than one X chromosome
turner syndrome
individuals often have 45 chromosomes with a single X chromosome
lyon hypothesis
inactivation of X chromosome is random, all descendant cell have same inactivation
x-inactivation
Dna, histone proteins, or both are chemically modified
imprinting
process whereby expression of genes on one homolog but the other is not affected
drosophila
has same sex chromosomes as humans, contains Y chromosome but has no role
C.elegans
has no Y chromosome
3x:2a and XY:3a
metafemale
3x:3a and 2x:2a
female
3x:4a and 2x:3a
intersex
x:2a and xy:2a
male
TSD
temperature-dependent sex determination
enzymes
steroids affected by temp
aromatase
converts androgens (males) to estrogens (female)
aneuploidy
organisms gain/lose one or more chromosomes but not a complete set
monosomy
loss of single chromosome from diploid genome
euploidy
complete haploid sets of chromosomes are present
polyploidy
more than two sets of chromosomes are present
nondisjunction
chromosomal variation originating from random errors during gamete production
trisomy (down syndrome)
extra chromosome produces more viable organism than loss of chromosome
autopolyploidy
addition of one or more sets of chromosomes identical to haploid complement of same species
allopolyploidy
combination of chromosome sets from species
inversions
genetic material is exchanged with segment of non homologous chromosome
translocations
location of genes altered within genome
deletion
missing region of a chromosome (terminal to intercalary)
cri du chat (5p-)
loss/deletion of small variable part of short arm on chromosome
duplication
repeated segment of chromsome
rRNA
structural components of ribosomes for protein synthesis during translation
rDNA
DNA that codes dor rRNA
fragile x syndrome
individuals bearing folate-sensitive site on X chromosome
linked genes
certain genes segregate as if somehow joined or linked together
linkage
synapsed homologous pairs reciprocally exchange chromosome segments
independent assortment
two pairs of chromosomes each with heterozygous gene pair
Single crossover
occurs between two nonsister chromatids to determine distance
double crossover
double exchanges of genetic material
product law
probability of two independent events
interfence
reduces expected number of multiple crossovers when crossover event in one region of chromosome inhibits second event nearby
positive # of Interfence
fewer DCOs than expected occur
negative # of interfence
more DCOs than expected occur
DNA markers
short segments of DNA with known sequence and location
SNPs
variation in single nucleotides found throughout genome
cystic fibrosis
found on chromosome 7 on long arm (q)
bacteria
prokaryotes
bacteriophages
viruses that use bacteria as their host
vertical gene transfer
transfer of genetic information between members of the same species
conjugation
genetic information from one bacterium is transferred to and recombined with another bacterium
F+ cell (fertility)
cells serve as donors of parts of their chromosome
F- cells
recipient bacteria receive donor DNA and recombine part of their own chromosome
plasmid (F factor)
autonomous genetic unit/ double-stranded closed circle
RTF
encodes genetic information essential to transferring plasmid between bacteria
r determinants
confer resistance to antibiotics or mercury
transformation
provides mechanism for recombination of genetic information in bacteria
lysogeny
virus enters bacterial cell and coexists with it
prophage
viral DNA that integrates into bacterial chromosome
virulent phages
viruses that only lyse cell
temperate phages
viruses that lyse cell or behave as prophages
transcription
synthesis of RNA from information in DNA
translation
uses information in mRNA to synthesize proteins
purines (9 double ring)
adenine and guanine
pyrimidines (6 single ring)
cytosine, thymine, uracil
RNA
contains ribose sugar
DNA
contains deoxyribose (without oxygen)
nucleoside
contains nitrogenous base and pentose sugar
nucleotide
nucleoside with phosphate group added
phosphodiester bonds
linkage between two mononucleotides involves a phosphate group linked to two sugars
Watson and Crick model
proposed DNA as double helix and paired nitrogenous bases and has major and minor grooves
mRNA
carry genetic info from gene to ribosome
tRNA
carry amino acids to ribosome for protein synthesis
semiconservative
each replicated DNA molecule consists of one "old" and one new strand
conservative
two newly synthesized strands come together
dispersive
parental strands are dispersed into new double helices
Meselson and Stahl
showed that semiconservative replication was the mode used by bacteria for replication
telomeres
long stretched of short repeating sequences preserve the stability of chromosome
Frederick Griffith
experiments with smooth, virulent strain Streptococcus pneumoniae and rough, nonvirulent strain
Griffith Model
transformation of bacteria that transfer genetic material
Avery, MacLeod, and McCarty
determined that DNA is the transformation material
Hershey and Chase
provide convincing evidence that DNA is genetic material
P
for DNA 32
S
for protein 35
Watson-Crick Model
propose their double helix model of DNA structure
B DNA
right handed helix