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