Classical Genetics and Evolution Flashcards
Define: allele
Alternative forms of an observable characteristic (For example, skin color would be the observable characteristic. Its alleles are the genotype that represents the dark or light skin colors.)
Define: genotype
Genetic makeup coding for a phenotype
Define: phenotype
Physical manifestation of the genotype (the phenotype is observable, while the genotype is the genetic makeup that codes for that observable trait)
Define: homozygous
Two identical alleles for the same trait (example: rr,RR)
Define: heterozygous
Two different alleles for the same trait (example: Rr)
What is the Law of Dominance?
The dominant allele is the one expressedin the phenotype
What is the One Gene One Polypeptide Hypothesis?
This hypothesis states that each polypeptide makes up only one gene of the many genes that code for a protein. Previously, it was believed that each polypeptide coded for an entire protein, also known as the Monocistronic Hypothesis.
What is the Monocistronic Hypothesis?
One gene is coded for by only one protein
Define: P generation
The P generation is the generation that consists of the individuals being crossed (parents)
Define: F generation
The F generation is the resulting generation from a cross
What is a progeny?
It is another name for the F generation
What is a trisomy?
Three copies of a chromosome rather than the normal two copies (example: down syndrome is caused by a trisomy of chromosome 21)
What is a monosomy?
One copy of a chromosome rather than the usual two copies
What is a monohybrid cross?
A cross, where only one trait can be studied
What is a testcross?
It is used to determine whether a phenotypicallydominant trait is homozygous or heterozygous. Both Rr and RR would produce dominant phenotypes. A testcross is used to determine whether the genotype is RR or Rr.
What is a backcross?
A cross between one individual from the F generation and one individual from the P generation
What is a punnett cross?
A method to predict the genotype of an expectedcross
What is the Law of Independent Assortment?
A law that states that genes on the same chromosome will stay together unless crossing over occur
What is a dihybrid cross?
A cross, where two traits can be studied.
Define: Incomplete Dominance
An allele is incompletely dominant if thephenotype of the heterozygous is intermediate of the homozygous phenotypes. (For example, if redwere crossed with white, the intermediate would be produced, pink.)
Define: Codominance
Codominance happens when more than one dominate allele exists and more than one of them is dominant. (For example, if red were crossed withwhite, then a striped individual would be produced since both colors are dominant.)
Define: Epistemic
A gene, which its expression is dependent onanother gene’s expression.
What is the 4 laws that Mendel came up with as the basis for genetics?
1.Genes exist in alternative forms (alleles)2. An organism has two segregated alleles from each parent for eachsomatic trait.3. Gametes cells are haploid4. Alleles are either Dominant or Recessive.
Define: Autosomes
The sex of organisms is determined by the combination of homologous sex allele i.e. XX or XY) XY= male; xx= females 22 somatic chromosomes + 2x = females 22 somatic chromosomes+ 1x +1Y = Male
How is Sickle Cell Anemia passed down?
Autosomal Codominant
How is Huntington Disease passed down?
Autosomal Dominate
How is Hemophilia passed down?
Sex linked Recessive on X (Males have no way of being a carrier)
How is Polydactylism passed down?
Autosomal Dominant
How is PKU passed down?
Recessive Autosomal gene
How is Tay Sacs passed down?
o Recessive Autosomal geneo Down Syndromeo Three copies of chromosome 21
How is Klinefelter passed down?
XXY (one extra X chromosome
How is Albinism passed down?
Autosomal Recessive
How is Tunrer Syndrome passed down?
Females with only one X rather than two
What is the Rh incompatibility?
It happens when the mother is RH- and is pregnant with a child that has RH+. This causes the mother’s blood to attack the child’s blood, thinking it is a foreign body. This usually causes more problems in the second pregnancy or later pregnancies.
Define: chromosomes
A long chain of DNA
Define: Chromatin
It is a small segment of Histones + DNA loose structures DNA during the interphase is referred to as chromatin due to its loose structure.
Define: Nucleosome
It is a long segment of chromatin. The analogy ofbeads on a string is usually used to refer tonucleosomes.
Describe the stage of interphase in mitosis
• Most cells are in the interphase stage• Cells that do not divide are always in G0 stage
Describe the G1 stage of interphase in mitosis
G1 Stage initiates interphase. The length of this stage determines the length ofthe entire cell cycle
Describe the S stage of interphase in mitosis
S Stage: the period of DNA synthesisDuring the S phase, whether during mitosis or meiosis, there is always 4n’s. During mitosis, those 4n’s divide once to become 2 2n’s cells (diploid). Each of these new cells would have the complete 46 chromosomes as the parentdoes.
Describe the G2 stage of interphase in mitosis
The cell gets ready to divide, synthesize protein, and grow.
Describe the Prophase stage of interphase in mitosis
Centrioles separate• Spindle apparatus form• Membrane dissolves• Spindle fibers appear• The two chromatids formed condense
Describe the Metaphase of interphase in mitosis
Spindle apparatus attaches chromatids