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