Lecture 3a and b: Flashcards
Epigenetic inheritance primarily occurs through…
meiosis
Two or more genes derived from a common ancestor are
Homologous
Homologous genes within a single species are (have a common ancestor)…
paralogs
Different paralogs carry out ____ functions
similar but distinct
the branch of biology linking the study of genetic inheritance
with the study of cell structure, especially for human
chromosome analysis for the detection of inheritable diseases.
Cytogenetics
A karyotype is
the ___
chromosomes
photographed and
arranged from
largest
to smallest
mitotic
Shortest chromosome is seen in….
anaphase
Chromosomes can be classified according to the
location of the centrosome
Middle centromere location
Metacentric
Longer arm and shorter arm on chromosome
submetacentric
Very short arms on a chromosome
Acrocentric
Humans don’t have any ___ centromeres, but mice do
Telocentric
What occurs in Robertsonian Translocations
the long arms of two acrocentric chromosomes have fused
One example of a Robertsonian translocation is
Familial Down Syndrome
In Familial Down Syndrome, the translocation is always between chromosomes….
14 and 21
Simple translocation involves a
DNA swap
Reciprocal translocation involves
2 chromosomes that swap arms
A chromosomal duplication is usually caused by
abnormal recombination
Misaligned crossovers occur at what sites?
Recombination at sites of homology
when 2 chromosomes shear at the same time, dna repair enzymes recognize broken ends and incorrectly connect them
reciprocal translocation
Reciprocal translocation can occur from ____ crossover
nonhomologous
What chromosome is different between homo sapiens and pan troglodytes (chimps)
2
At chromosome 2,
In chimps:
In humans:
In chimps: both acrocentric
In humans: 1 acrocentric
What chromosomes fused in humans that didn’t in chimps
2a and 2b
DNA consists of two complementary strands
held together by
h bonds
phenomenon in which sections of the
genome are tandemly repeated and the number of repeats in the
genome varies between individuals.
copy number variation
Approximately ____ of the human genome is subject to copy number variations (such as segmental duplication)
5%
A hybridized fluorescent probe is used on what kind of chromosome?
metaphase (mitotic)
Process of fluorescent hybridizing chromosomes
Heat up chromosome, add short single stranded DNA with a fluorescent chemical, and cool it down
How many bases does it take to have a unique address in a chromosome
20-25
Dna winds around what protein
histone
DNA Fluorescent In Situ Hybridization (DNA FISH) to what chromosomes
to mitotic chromosomes and to interphase chromosomes
Some specific translocations occur quite frequently such as the fusion of
BCR and ABL1 (philadelphia chromosome)
every chromosome has a differently
colored chromosome paint
Spectral Karyotyping (SKY)
Most species of animals are
diploid
___ in animals is generally a lethal condition
Polyploidy
Male bees (drones) are…
monoploid
In many instances, ___ strains of plants display outstanding agricultural characteristics
polyploid
If polyploid plants have an ___ number of chromosome sets, they are usually sterile
odd
Polyploid plants that have an odd number of chromosomes produce highly….
aneuploid gametes
What in polyploidy is usually a detrimental trait
sterility
Sterility can be agriculturally desirable
because it may result in:
Seedless fruit and flowers
There are three natural mechanisms by
which the chromosome number of a
species can vary….
- Meiotic nondisjunction
- Mitotic abnormalities
- Interspecies crosses
refers to the failure of chromosomes to segregate properly during anaphase
nondisjunction
Meiotic nondisjunction can produce what kind of cells
haploid cells that have too many or too few chromosomes (aneuploid)
In meiotic nondisjunction: if such a gamete participates in fertilization, the resulting individual will have an…
abnormal chromosomal composition in all of its cells
Nondisjunction in meiosis 1 vs meiosis 2
Meiosis 1: ALL 4 GAMETES abnormal
Meiosis 2: half of gametes normal and half abnormal
Nondisjunction in meiosis 1 vs meiosis 2
Meiosis 1: ALL 4 GAMETES abnormal
Meiosis 2: half of gametes normal and half abnormal
Abnormalities in chromosome number
often occur after fertilization in…
mitosis
If a mitotic abnormality doesn’t kill the cell, then the person with the cell can become a
mosaic
Sister chromatids separate improperly
Mitotic disjunction
Leads to trisomic and monosomic daughter cells
Mitotic disjunction
One of the sister chromatids does not migrate to a pole
chromosome loss
What are the two mitotic abnormalities
- Mitotic disjunction
- Chromosome loss
A much more common mechanism for changes in
the number of sets of chromosomes is
alloploidy
In mitotic disjunction, the chromosomes are pulled by…
deploymerization
What is the result of interspecies crosses?
alloploidy
No synapsis between the 9 radish and 9 cabbage chromosomes in what variant
allodiploid
proper synapsis between the 18 radish chromosomes and the 18 cabbage chromosomes in what variant
allotetraploid
individual cells are mixed together and
made to fuse
cell fusion
Cell fusion can create new strains of…
allotetraploid plants
It allows the crossing of two species that cannot interbreed
naturally
cell fusion
Cells without cell walls
protoplasts
cells with two seperate nuclei
heterokaryon
We think that the road to life began with
a polymer called
RNA
In both RNA and DNA, a base and
a sugar (no phosphate) is called a
nucleoside
The sugar of an RNA nucleotide is called
ribose
Ribose consists of a ring of ___ carbon atoms and ___ oxygen plus ___ more carbon
4, 1, 1
The adenine and guanine bases are
purines
The uracil and cytosine bases are
pyrimidines
The RNA nucleotides that are precursors to RNA
polymers have ___ phosphates
and are called
3, tri-phosphates
In the covalent bonds linking oxygen to hydrogen and
nitrogen to hydrogen the, ___ have
stronger affinities for the shared electrons than ___
oxygen and nitrogen, hydrogen
What bond: The partial negative charges of oxygen and nitrogen
attract hydrogens with partial positive charges
hydrogen bonds
It always takes ___ atoms to make an H-bond.
3
What bonds are important in the 3D structure of RNA: folds back on each other and base pairs
H bonds
Some longer RNA molecules are able to catalyze
chemical reactions if they have nucleotide sequences
that make them fold in a way that creates
catalytic sites
1st enzymes ever
RNA
Refers to a period on Earth in which RNA molecules,
but not DNA or proteins, were replicating
RNA world
In RNA world, RNA would have carried out three functions:
catalytic activity, self-replication, info storage