Biology 1151 14-17
Chargaff's Rules
1) The base composition of DNA varies between species 2) In any species the number of A and T bases are equal and the number or G and C bases are equal
trisomy
2n+1
monosomy
2n-1
Duplication
?
Monohybrid
?
Monohybrid cross
?
What kind of cross(s) will give you these ratios 3:1,9:3:3:1,1:1:1:1,1:1
?
Turner's syndrome
A chromosomal disorder in which a female is born with only one X chromosome--manly
Red-green color blindness is located on X chromosome
A color blind (recessive) woman will pass this trait onto all of her offspring
Dihybrid cross
A cross between two organisms that are each heterozygous for both of the characters being followed. (or the self-pollination of a plant that is heterozygous for both characters)
Kleinfelter's syndrome
A genetic condition in which a male is born with an extra copy of the X chromosome--feminine
The F1 offspring of a monohybrid cross would show the genotype(s)
Aa only
Cystic fibrosis
An inherited life-threatening disorder that damages the lungs and digestive system.
In humans, presume brown eyes (B) are simple dominant-over blue eyes (b). A brown eyes woman who has a blue eyed child would have the genotype
Bb
Difference between DNA and RNA?
DNA is a long polymer with deoxyriboses and phosphate backbone. A, C, G, T RNA is a polymer with a ribose and phosphate backbone. A, C, G, U
Structure of DNA
Deoxyribose sugar + N-Base + P04 = Nucleotide Deoxyribose sugar + N-base = Nucleoside
In a Mendelian monohybrid cross, the ____ generation is always completely heterozygous
F1
Dominant Allele
Fully expressed in the phenotype of a heterozygote
Multiple Allele Inheritance
Gene exists in many allelic form; but each person has (usually) only 2 of the possible alleles. Ex: bloodtype A,B,O,AB
WW, Ww, ww
Homozygous dominant, Heterozygous dominant, homozygous recessive
Mendel's law of independent assortment
Mendel's second law, stating that each pair of alleles segregates, or assorts, independently of each other pair during gamete formation; applies when genes for two characters are located on different pairs of homologous chromosomes, or when they are far enough apart on the same chromosome to behave ad though they are on different chromosomes.
Mendel's law of segregation
Pairs of factors separate independently of other pairs of factors during gamete formation Mendel's first law, stating that the two alleles in a pair separate from each other into different gametes during gamete formation
Recessive Allele
Phenotypic effect is not observed in a heterozygote
Nitrogen bases
Purines (2rings): Adenine & Guanine Pyrimidines (1ring): Thymine(uracil) & Cytosine
Which of the following crosses will yield 4 phenotypes in the 1:1:1:1 ratio?
RrYy x rryy
RNA (ribonucleid Acid)
Structure = Single stand: polynucleotide Sugar = Ribose sugar
DNA (deoxyribose nucleic acid)
Structure: double strand helix, sugar phosphate backbone Sugar: Deoxyribose
Genetic disorders
Tay Sachs disease, color blindness, hemophilia, Huntingtons disease, cystic fibrosis
Types of RNA
Transfer RNA (nucleus) Messenger RNA (cytoplasm) Ribosomal RNA (nucleolus)
Genotype of these crosses??
Tt x Tt, TtRr x TtRr, TtRr x ttrr (Dihybrid testcross), Tt x tt (monohybrid testcross)
Inversion
a kind of mutation in which the order of the genes in a section of a chromosome is reversed
locus
a particular position, point, or place--where gene is located on chromosome
Hemophilia
absence of one or more proteins required for blood clotting
allele
alternative forms of a gene that influence the same trait and are found at the same location in homologous chromosomes (single trait)
genetic map
an ordered list of the genetic loci along a particular chromosome
Autosome
any chromosome that is not a sex chromosome
Mendel's law of segregation implies that the two members of an allelic pair
are distributed to separate gametes
Testcross
breeding an organism of an unknown genotype with a recessive homozygous
Importance of karyotype
can be used to diagnose genetic disorders--down syndrome
mRNA
carries the genetic information copied from DNA in the form of a series of three-base code "words," each of which specifies a particular amino acid
rRNA
catalyze the assembly of amino acids into protein chains. They also bind tRNAs and various accessory molecules necessary for protein synthesis.
Transformation
change in genotype and phenotype due to assimilation of foreign DNA
Translocation
change to a chromosome in which a fragment of one chromosome attaches to a nonhomologous chromosome
Deletion
change to a chromosome in which a fragment of the chromosome is removed
Chromatin
complex of DNA and protein. Found in the nucleus of eukaryotic cells
nondisjunction
error in meiosis in which homologous chromosomes fail to separate
Gamete formation
formed during meiosis
tRNA
function at specific sites in the ribosome during translation, which is a process that synthesizes a protein from an mRNA molecule (desiphers mRNA)
epistasis
gene at one locus alters the phenotypic expression of a gene at a second locus
pleiotropy
genes with multiple phenotypic effects
F1 generation is always ____
heterozygous
Dihybrid
heterozygous for 2 characters being followed in the cross. All the offspring from a cross between parents doubly homozygous for different alleles are dihybrids. For example, parents of genotypes AABB and aabb produce a dihybrid genotype AaBb.
family pedigree
history for a particular trait (family tree)
A testcross occurs when an individual with the ____ is crossed with an individual having the ____
homozygous dominant heterozygous recessive
If pairs of factors separate independently of other pairs of factors, you are dealing with
law of segregation
DNA replication
maintains genetic information begins when Helicase breaks the H-bonds that connect a base pair
multifactorial
many factors, genetic and environmental, collectively influence phenotype
In which kind of cross would you expect to find a ratio of 3:1 among the F2 offspring?
monohybrid cross
chorionic villus sampling
narrow tube inserted through cervix and sucks a sample of placenta
amniocentesis
needle is inserted into the uterus and extracts amniotic fluid
Nucleotides consist of
nitrogenous base, sugar, and phosphate group
For Mendel's law of segregation to occur, the alleles must be
on a homologous pair of chromosomes
If an organism shows a recessive phenotype, such as a short pea plant, it can be
only tt
Phenotype
organisms appearance or observable traits
Genotype
organisms genetic makeup
Homozygous
pair of identical alleles for a character/gene
Mendel carried out most of his research with
pea plants
norm of reaction
phenotypic range for a genotype
genetic recombination
the regrouping of genes in an offspring that results in a genetic makeup that is different from that of the parents
codominance
two alleles affect the phenotype in separate, distinguishable ways
Heterozygous
two different alleles for a character/gene
quantitative characters
vary in the populations in gradations along a continuum--usually indicated polygenic inheritance
Bacteriophages
viruses that are widely used in molecular genetics research
Karyotype
visual examination of chromosomes