Biology Final

Leeuwenhoek

proposed that sperm contained a miniture human that he called a homunculus and the mother only served as the incubator “spermists”

DeGraff

proposed that the egg contained the human and the sperm only served to stimulate growth “ovists”

Blending Theory

This theory suggests that traits from both parents blend together in the offspring, resulting in a combination of characteristics that reflect an average of the traits of the parents.

Particulate Theory of Heredity

parents transmit their offspring discrete inheritable factors that remain as seperate factors from one generation to the next

Gene

discrete unit in the DNA of a chromosome which carries the hereditary information for each character; in a diploid organism its represented by two alleles

Allele

variant of a gene

Locus (loci)

specific location on the chromosome that contains an allele

Character

inheritable feature (e.g. flower color, eye color, nose shape

Trait (allele

variant of character

homozygous

having two indentical alleles for a given gene

heterozygous

having two different alleles for a given gene

dominant allele

the allele that is fully expressed in the phenotype on an heterozygous organism

recessive allele

the allele that is completely masked in the phenotype on an heterozygous organism

Punnett Square

way of predicting the combinations resulting from random genetic crosses

Monohybrid Cross

a genetic cross between individuals that differ in a single trait, typically involving one pair of alleles; Mendel deduced his first law, the Law of Segregation

Mendel’s Law of Segregation of Alleles

states that during the formation of gametes, the two alleles for a trait separate from each other so that each gamete carries only one allele for each gene.

Dihybrid cross

a genetic cross between individuals that differ in two traits, typically involving two pairs of alleles.

Law of Independent Assortment

states that the alleles for different traits segregate independently of one another during gamete formation.

Semi Conservative Replication

where two strands of the original double helix separate and each strand functions as the template for the synthesis of a new complementary strand

Conservative Replication

the original double helix gets bak together after replication there the new double helix lacks any of the new one

Dispersive Replication

The two strands of the original double helix separate and each strand of both daughter molecules contains a mixture of old + newly synthesized DNA

True Breeding Variety

a variety that when it self-pollinates the offspring are the same as the parents, generation after generation

Polymers

covalently linked monomers

Van der Waals Interactions

weak attractions that attract neutral molecules to one another

structural isomers

C skeletons are different, covalent arrangements are different, but formula is the same

trans isomer

the x’s are on opposite sides

cis isomer

the two x’s are on the same side

Pauli Exclusion Principle (in relation to atomic orbitals)

an orbital can hold a maximum of two electrons with opposite spins

Helicase

enzymes that untwist the double helix at the replication fork separating the two strands and making them available as templates

Topoisomerase

an enzyme that breaks, swivels, and rejoins DNA strands. During DNA replication it helps relive strain on the double helix ahead of the replication fork

single strand binding proteins

proteins that bind the the unpaired dna strands during replication, stablizing them and holding them apart while they serve as templates for the synthesis of the complementary dna strands

Primase

an RNA polymerase that joins RNA nucleotides to make primer using the parental DNA strand as a template strand

DNA polymerase III

a complex of enzymes that catalyzes the elongation of new DNA by adding nucleotides to the 3’ end of the existing chain. Elongates in the 5’ to 3’ direction.

DNA polymerase I

an enzyme that removes and replaces the RNA primer

Ligase

an enzyme that ligates the ends of dna molecules (glue)

Griffith’s Experiment

Pneumonia, S bacteria, R bacteria, Bacterial transformation, the basis of the recombinant molecular technology we use today in lab

Avery+McCarthy+MacLeod’s Experiments

suggested that the dna is the genetic material, however they only had indirect proof

Chargaff’s Experiment

Found that DNA is composed of sugar, phosphate, and 4 nitrogenous bases

Hershey+Chase’s Experiment

worked with bacteriophanges-viruses that infect bacteria to determine whether it was the DNA or protein fo the virus that entered bacterial cells to direct replcation; used radioactive isotopes P-32 for DNA and S-35 for protein; (blending and centrifugation) concluded only DNA entered the bacterial cells, not protein

Watson’s Deductions from Franklin’s Data

dna molecule is 2nm in diameter, 1 nm per strand; the bases in DNA were 0.34nm apart; the helix makes one full turn at every 3.4nm; ten base pairs per turn

Watson+Crick’s Experiment

Proposed that DNA is a double helix with antiparallel strands; DNA consisted of 4 nitrogenous bases; heavily based on data from Rosalind Franklin. Their model explained how DNA replicates before cell division.

Meleson + Stahl’s Experiments

Provided proof DNA replication is semi-conservative. Experimented with heavy and light nitrogen (15 and 14 respectively); Extracted DNA spun in a cesium chloride density gradient centrifuge to separate DNA based on weight.

Nondisjunction

can occur during both meiosis I and II with different consequences for the number of chromosomes in the gametes

Chromosome alterations

Inversion, deletion, duplication, translocations