Midterms Reviewer Flashcards
Phenotypic expression of a pair of alleles depends on?
Combination and their mode of inheritance?
What is Gene Interaction?
It is where phenotypic expression of a gene or an allele is either MASKED or ALTERED by another gene or allele.
Gene interaction that is particularly involved in suppressing the expression of a gene or allele.
Epistasis
Either dominant from both pairs of alleles will allow the expression of the trait
Duplicate Gene Interaction (15 : 1)
Both dominant alleles from each pair will allow the expression of the trait. Also known as double recessive epistasis because the presence of any pair of recessives will prevent the trait from being expressed.
Complementary Gene Interaction (9 : 7)
Type of gene interaction where the expression of a trait in one gene is masked by the recessive allele of the other gene
Single Recessive Epistasis (9 : 3 : 4)
Type of gene interaction where the expression of one pair of alleles is masked by a dominant allele from the other pair
Dominant Epistasis (12 : 3 : 1)
Type of gene interaction where an allele prevents the expression of the other pair of alleles
Dominant Suppressor Epistasis (13 : 3)
Type of Pedigree Analysis where the abnormal allele is dominant, and the normal allele is recessive.
Autosomal Dominant Pedigree Analysis
Type of Pedigree Analysis where the abnormal allele is recessive, and the normal allele is dominant.
Autosomal Recessive Pedigree Analysis
Type of Pedigree Analysis where the abnormal allele is sex linked recessive, and the normal allele is dominant.
X-linked Recessive Pedigree Analysis
Type of Pedigree Analysis where the abnormal allele is sex linked dominant, and the normal allele is recessive.
X-linked Dominant Pedigree Analysis
Type of Pedigree Analysis where the abnormal allele is on the Y chromosome.
Y-linked Pedigree Analysis
It refers to the physical association of genes on the same chromosome.
Gene linkage
Genes that are located on the same chromosome are called?
Linked Genes
Genes that are located on the same chromosome are called?
Linked Genes
All the genes present in a chromosome are known as what?
linkage group.
How many Linkage and sex-linked groups in humans; in Females? and Males?
Female
23 linkage and 1 sex-linked
Male
24 linkage groups
Genes that are closer to each other have a greater tendency of being inherited together during crossing-over. This is because they are?
genetically linked.
It shows the location (locus) of physically linked genes on a chromosome in a linear arrangement.
Genetic map
It refers to the precise location of the gene on the DNA as well as its size, based on the sequence of complementary base pairs. It also helps determine the exact distance between the linked genes.
Molecular Location
This determines the cross-over data which shows the way of mapping the location of a gene in a chromosome.
Recombination Frequency (Rf)
What is the possibility of recombination if genetically linked genes are so close together that they are never separated, even during crossing-over
zero
Genes that are not genetically linked (farther from each other) have a tendency of?
Being unlinked during crossing-over.
If the genes were separated during crossing over, 50% of the gametes would contain separate copies of the genes and their chromosomes are called?
recombinant chromosomes.
The other 50% of the gametes would contain both copies of the genes because there was no crossing-over involved. Their chromosomes are the same as the chromosome of the parent cell, thus referred to as?
parental chromosomes
This method is used to determine both the location of genes and their distances from each other. It requires three linked genes.
Three-point Cross
Three-point cross; state three possible events that happen to non-sister chromatids during meiosis.
(a) No crossing -over (NCO)
(b) Single crossing -over (SCO)
(c) Double crossing -over (DCO)
In what specific stage of the cell cycle does DNA replication occur?
S-Phase
if crossing over does not occur, how many types of gametes will be formed, based on the alleles present?
2
if crossing over occurs, how many types of gametes will be formed, based on the alleles present?
4
It is the exchange of genetic material between homologous pairs.
Crossing-Over
A DNA molecule found in the nucleus that carries the genetic material.
Chromosomes
The chromosome is made up of what?
two identical sister chromatids
The sister chromatids attached at a point called the what?
centromere
The centromere constricted portion divides the chromosome into two sections called the what?
arms
What are two types of arms?
p arm and q arm
The location of the centromere is the basis for classifying the chromosomes. State four types.
A. Telocentric
B. Acrocentric
C. Submetacentric
D. Metacentric
Chromosome type that has a centromere at the tips of the chromosome.
Telocentric
Do humans possess telocentric chromosomes?
No, but other mammals do.
A chromosome that has centromeres located quite near the tip of the chromosome.
Acrocentric
Chromosomes that have a centromere located near the middle, resulting in a slightly unequal arm.
Submetacentric
A chromosome that has a centrally located centromere with p and q arms of almost the same length.
Metacentric
A single chromosome contains how many DNA molecules?
One
What allows the DNA molecule to be supercoiled?
Histones
Describe DNA by the number of strands, manner or formation, and shape.
A DNA molecule is made up of two DNA strands arranged in an antiparallel manner and twisted into a double helix
The nucleoside is made up of?
a sugar and a nitrogenous base
State the composition of Nucleotides
A. Phosphate Group
B. Sugar Group
C. Nitrogenous Base
What are the types of bonds found within a nucleotide
Nucleotide bases form hydrogen bonds
Glycosidic bond within a nucleoside
Sugars are connected via ester bonds
What forms complementary base pairs?
Purines and Pyrimidines
Group of proteins responsible for DNA packaging
Histones
What do you call pairs of histones,
What are the four types,
these form form a?
Dimers;
H2A, H2B, H3, H4
forming an octamer
Proteins that participate in DNA packaging
Non-histone proteins
The average length of one DNA molecule is approximately how many cm?
5 cm
How many DNA’s per cell
46
The first level of DNA packaging is the formation of what?
Nucleosome
A series of nucleosomes form this structure that looks like “beads on a string”
chromatin
What histones allow the 2 nm diameter DNA to wind around the tetramer once. What is formed from this process?
H3 and H4.
A tetrasome is formed
What are the more reliable packaging histones that allow DNA to form a negative superhelical turn around a histone octamer twice, forming this structure?
2A and 2B
It forms a nucleosome
Between adjacent nucleosomes is a short DNA segment called the what?
linker DNA
What histone is associated with the linker DNA. which promotes further coiling by compacting the nucleosomes into a 30 nm chromatin?
H1
What are the two possible configurations for chromatin?
Solenoid and Zigzag Models
The third level of compaction
Euchromatin
What two structures interact with each other to form the euchromatin?
30 nm fiber and the nuclear matrix
A special feature of the euchromatin
Radial loops
The anchor to the nuclear matrix via internal matrix proteins, forming a loop
matrix attachment regions
Further compaction of the 300 nm euchromatin forms a? (Include measurement)
700nm heterochromatin
T or F: Transcription occurs in heterochromatin segments
False
Permanently inactive heterochromatin. Formed by DNA segments that are no longer used or needed by the cell
Constitutive Heterochromatin
Inactive for sometime then uncoils back to euchromatin if the transcription is required by the cell, then coils again into a heterochromatin
Facultative Heterochromatin
T or F:
During the prophase stage of cell division, the chromatin enters the last level of compaction
True
All euchromatin coils into heterochromatin, then all heterochromatin undergoes supercoiling to form the?
Chromosome