Exam 1 Flashcards
Define Genetics
The study of genes/heredity/ and genetic variation (in living organisms)
characteristics of model organisms
short generation time, production of numerous progeny, ability to vary out controlled genetic crosses, ability to be reared in a laboratory environment, availability of numerous genetic variants, already have an accumulated body of knowledge about their genetic systems
Prokaryotes
no membrane bound nucleus or organelles, relatively small, (usually) one circular DNA molecule with NO histones, DNA is organized in a nucleoid region (but no nucleus)
How do prokaryotes replicate?
binary fission
Eukaryotes
has a nucleus, relatively large, multiple linear DNA molecules and have histones, has membrane-bound organelles
Organization of Eukaryotic DNA
tightly packed into linear chromosomes which are further organized into chromatin (DNA wrapped around histones)
Viruses
are composed of proteins as the outer coat and nucleic acid inside (they are not PRO or EUK)
Diploid unreplicated chromosomes
a haploid product of meiosis would only contain ONE of these unreplicated chromosomes. Let’s say the grey one is from mom and the black one is from dad; the products of meiosis will only have 1 (mom’s chromosome OR dad’s, not both (unless nondisjunction occurs))
Diploid replicated chromosomes
Nondisjunction in Meiosis 1
Nondisjunction in Meiosis 2
Karyotype
visual display of an individual’s chromosomes
Genotype
the set of alleles in an individual organism
Phenotype
the observable characteristics in an individual (when one allele gets expressed over the other, we see it in the phenotype)
Gene
Genetic factor that helps determine a trait
Allele
a different form of a gene
Locus
a specific place on a chromosome where an allele takes place
Homologous chromosomes
chromosomes with the same genes (but can have different alleles). One chromosome in each homologous pair is from the mother, and one is from the father.
Which phase in Interphase does the DNA get replicated? G1, S, or G2?
S (synthesis)
In which phase do the homologous chromosomes meet up?
Only in Prophase 1 of meiosis
In which phase do the homologous chromosomes separate?
Only in Anaphase 1 of meiosis
In which phase do the sister chromosomes separate?
In Anaphase of Mitosis, and in Anaphase 2 of Meiosis (the cohesion protein holding them together had to break down in order for the sister chromatids to separate)
Products of Mitosis
produces two cells that are genetically identical to each other (and to the parent cell)
Products of Meiosis
Produces haploid gametes that are genetically different from the original cell (and from each other)
In which phase of Meiosis can crossing over occur?
In prophase 1 of Meiosis (the homologous chromosomes meet up with each other only in prophase 1 of meiosis 1 until the get pulled apart in anaphase 1)
What type of chromatids can crossing over occur in?
Crossing over can only occur between non-sister chromatids
Concept of Independent Assortment
Genes on non-homologous chromosomes will line up independently of each other (for example, chromosome 1 (who contains the alleles A and a) and chromosome 2 (who contains the alleles B and b) will line up at the metaphase plate anywhere regardless of each other)
Law of segregation
The alleles separate (in anaphase 1 of meiosis) as they into the two new cells and form gametes
If an individual has the genotype AaBb for a dihybrid cross, what are that individual’s gametes?
AB, Ab, aB, and ab
If an individual has the genotype Aabb for a dihybrid cross, what are that individual’s gametes?
Ab and ab
If an individual has the genotype aabb for a dihybrid cross, what are that individual’s gametes?
ab only
If we crossed the AaBb and the aabb, how would we set up the Punnett square?
Probability, Multiplication Rule;
When crossing AaBbcc x aabbcc, what is the probability of getting aabbcc?
Probability, Multiplication Rule;
When crossing AaBbcc x Aabbcc, what is the probability of getting aabbcc OR A_B_cc?
the underscore means the second allele can be uppercase or lowercase
Set up the following problem with the formula P = (n!/s!t!)(p^s)(q^t)
In a family of 5 children, what is the probability of getting 5 boys and 0 girls?
Set up the following problem with the formula P = (n!/s!t!)(p^s)(q^t)
In a family of 5 children, what is the probability of getting 2 boys and 3 girls?
If you crossed two individuals with the genotype Bb, what is the probability that the progeny with the black fur will be homozygous for that allele? (B = black fur, b = gray fur)
If a mother is heterozygous for the color blind allele (X+Xc) and the father is not color blind (X+Y), what is the chances of their daughter CARRYING the blind allele? (the color blind allele is recessive)
Lethal alleles
An allele that causes death if the individual is homozygous for the lethal allele. The lethal phenotype is recessive because you NEED two of the lethal allele for the individual to be affected and die. The individuals who are heterozygous for the lethal allele are safe. (In the example below, the lethal allele is ‘y’)
We cross an individual with type IAiHh blood to an individual with type IBihh. (The Bombay blood group is epistatic and when the gene is recessive (hh), the other gene (blood type) gets masked and becomes blood type O). What is the probably the progeny will be blood type O?
