BIOL261 Midterm Flashcards
to analyze a genetic cross we observe
the frequency of phenotypes among offspring.
Mendel’s first Law states
two alleles of a gene segregate to separate gametes at random.
All combinations during recombination have
an equal chance of occurring.
3:1 ratio shows the trait is controlled by
one gene, two alleles.
Chromosomes have
genes.
RNA translated into
proteins.
Genes composed of
DNA.
Mutations lead to
non-functional proteins (enzymes).
Altered metabolism from mutations give rise to
phenotypes and diseases.
Diploid organisms have
two sets of homologous chromosomes.
Karyotype consists of
22 sets of autosomal chromosomes, and two sex chromosomes.
What are heteromorphic sex chromosomes in birds
inactivated W copy.
Define sex-linked inheritance
a trait controlled by a gene on either the X or Y chromosome.
Genes on the X chromosome are passed from fathers
to ALL daughters.
meiosis and mitosis in haploid organisms consist
of a single set of chromosomes in each cell.
are partially diploid.
meiosis produces haploid cell origin.
Mendel’s Second Law of
independent assortment. Applies to genes on different chromosomes, alleles close together on the same chromosome do not assort independently at meiosis.
Define linkage
the tendency of genes to be inherited together due to location on the chromosome.
How are genes arranged on a chromosome
in a linear order.
Define interference
inhibiting cross over likelihood.
The expected double recombinants in an experiment indicates
no interference.
coefficient of coincidence
how well observed results coincide with expected results.
if the coefficient is 0 there is
No interference. Interference is 1, because there are no double recombinants found meaning the crossover in one region really affected the crossover in another region.
Unlinked genes are
independently assorting genes.
State the null hypothesis in a Chi-Squared test
the genes are unlinked.
List three characteristic that a trait is controlled by genes
- Inheritance.
- Mendelian ratios.
- linkage to other genes, co-segregation.
Name two patterns in which bacteria follow
- Inheritance.
2. linkage to other genes, co-segregation.
List three type of mutants
I. Resistance to antibiotics.
II. Requirement for a nutrient.
III. cannot grow on a sole carbon source.
F+ is a
small, circular chromosome.
In Hfr the F factor is
integrated into their chromosome.
List four types of gene mapping in bacteria
- interrupted mating (measured in minutes).
- recombination frequency.
- transformation.
- transduction by phage.
Define transformation
introduction of chromosomal DNA by physical means.
Define interrupted mating
- partial transfer of genome.
- passes to recipient in linear order.
- distance between genes measured in minutes.
How do we separate two strains after mating
using selective media.
Define bacteriophages
- phages, bacterial viruses.
- have genes that are mapped.
Type of transducing phage
P1, for generalized transduction.
co-transducing gene mapping via
P1 phage.
The closer two genes are, the higher rate of co-transduction (T/F)
T.
The maximum distance in co-transduction is
2 minutes, 2 % of the bacterial genome.
Define one-gene-one-enzyme hypothesis
- introduced by Beatle and Tatum.
- proposed that genes encode for proteins, from the analysis of mutant Neurospora.
Define the biosynthetic pathway
- sequence of enzymatic steps in the synthesis of a specific end-product.
- complementation in pathway can occur.
Complementation determine
if mutation is on the same gene.
Complementation test for Neurospora
fusion creating heterokaryon.
Complementation test for E.coli
merodiploid, introduction of plasmid (episome).
Complementation test for phage
co-infection, recombination DNA.
Complementation test for eukaryotes
mating, recombination DNA.
List 4 variation of single gene traits
- incomplete dominance.
- codominance.
- multiple alleles.
- lethal alleles.
Define incomplete dominance
- no dominance observed.
- genotypic ratios remain.
- phenotypic ratio changes due to lack of pigment.
Define codominance
both alleles are expressed in heterozygote.
Define multiple alleles affecting a single gene trait
- ABO blood for example.
- A and B are codominant, third allele O is recessive.
Define a lethal allele
- deviates from Mendelian ratios.
- Allele can be dominant for trait but recessive for lethality.
List three variation of multiple genes affecting the same trait
- two genes give rise two segregation ratios.
- Epistatic genes.
- Duplicate genes.
Define epistatic genes
the expression of one gene overrides the other gene resulting in ratios deviating from Mendel’s phenotypic ratios (9:3:4 / 9:7).
Define duplicate genes
will give rise to 15:1 phenotypic ratio.
Name and define Griffiths principle
- “the transformation principle”.
2. could change the genotype of a non-virulent, causing it to a virulent.
Avery discovered
“the transforming principle” as DNA.
Hershey defined
DNA as the genetic material with T2 phage.
Chargaff’s rule
- relative frequencies of four nucleotides in DNA.
- A=T, C=G.
- A+G=C+T.
Meselson proposed that DNA is
semi conservative, by labelling isotopes of nitrogen and subjecting them to a centrifuge.
each chromatid before replication contains
single double-stranded DNA.
Function of DNA Pol III
carries out most of the synthesis of DNA on both leading and lagging strand.
Function of DNA Pol I
fills gaps in lagging strand with DNA.
Types of Primase
dnaB,T and priA,B,C
Function of ligase
contains RNA, and joins adjacent nucleotides by covalent bonds.
Function of helicase
breaks H-bonds between nitrogenous bases.
Type of covalent bond in DNA
phosphodiester bond.
Pol I/III perform
- exonuclease activity as in proofreading in reverse 3’–> 5’.
- remove bases from 3’–>5’, add bases from 5’–>3’.
Lagging strand is primed with
Ogazaki fragments.
Ogazaki fragments are made up of
short RNA fragments.
Type(s) origin(s) in bacteria
- single origin.
- autonomously replicating.
Type(s) origin(s) in eukaryotes
-many origins.
Replication occurs at
S phase.
Define telomeres
at the ends of the lagging strand.
Function of telomerase
- replicates DNA at the end.
- contains its own RNA template, serving as template for DNA synthesis.
- works on parent strand only.
- particular telomere sequence.
- last 2 bases attach, elongating parent strand.
- makes sure that actual DNA isn’t being cut off.
What is overhang flap in DNA sequence
junk DNA synthesized by telomerase.
