Module 2 Flashcards
What biological process explains Mendel’s law?
Meiosis
What are the products of segregation after meiosis?
4 chromatids
What is segregation?
A mechanism to generate variability
How many possible random segregation combinations are there for humans?
2^23 = 8,388,608
What is the unit of segregation?
Chromosomes
What is the determinant factor for male reproductive development?
SRY gene
What are female chromosomes?
XX
What are male chromosomes?
XY
What would cause femaleness in XY individuals?
Deletion of the SRY gene
What is an example of X-linked recessive?
Colour blindness and hemophilia
What is an example of X-linked dominant?
Vitamin D resistant, brown teeth enamel
What do gene mutations affect?
Typically one gene
What is a large-scale chromosome change?
Chromosome mutation that affects many genes, leads to structural differences that can be detected using microscope
What is a karotype?
A collection all chromosomes (with a specific number and structure) of a species or individual in condensed state
What are cytogenetics?
Geneticists use stains to identify specific chromosomes and to analyze structures
What is a euploid?
Having a chromosome number that is an exact multiple of a monoploid number (1n)
What is a polyploid?
Extra copies of each chromosome of species (>2n, diploid, triploid, tetraploid)
What is an aneuploid?
Abnormal number of one or more chromosomes
What is the definition of monosomic?
One missing chromosome compared to 2n wild type
What are the effects of polyploids?
Part of normal development of certain tissues and organisms (human muscle tissue, bone marrow
What are the results of monoploids?
Part of normal development in some insects (wasps, bees), males are 1n, females are 2n
What are the results of monosomic?
Part of normal development in some organisms, sex determination in some nematodes (XX and XO)
What is autopolyploid?
All chromosomes originated from the same organisms
What is allopolyploid?
One set of chromosomes originated from one organism and other from another, parent organisms need to be related to produce viable progeny
Allopolyploidy in agricultural purposes
Mixing 2 genomes can lead to new phenotypes in offspring
Autopolyploidy in agricultural purposes
Increasing ploidy levels can generate traits more valued by consumer
How are autopolyploids generated naturally?
Naturally formed by mistakes in meiosis that lead to failure in executing one of the meiotic divisions and leads to gamete with twice as many chromosomes
How are autopolyploids induced/created?
Formed by hybridization; crosses between 2 related species (mostly plants), can be formed by chemically fusing 2 cells
What is the purpose of polyploid tissues in humans?
In some tissues, cells replicate DNA in S phase but not divide, leading to formation of polyploid tissue. eg) liver, heart, bone marrow, any smooth muscle
What is aneuploidy?
The addition or loss of less than a full set of chromosomes or chromosome pairs
What is monosomes?
One missing chromosome, in humans, autosomic monosomies die in utero; only one viable monosomy (Turner syndrome)
What are trisomies?
one extra chromosome, in humans, only autosomic monosomies for large chromosomes die in utero, few viable trisomies (Klinefelter syndrome, down syndrome)
Turner syndrome chromosomes
XO
Turner syndrome characteristics
sterile females
tall, slightly feminized
poor facial hair growth
small testis, female type pubic hair
Down Syndrome is also known as
Trisomy 21
Down syndrome effects which chromosome?
21 non-disjunction/translocation
What is the idea of gene dosage?
Products of genes typically do not work in their own pathway, but interact with others to contribute to process or pathway
What are some origins of chromosomal rearrangements?
Deletions, duplications, inversion, translocation
What is needed for rearrangement of chromosomes to happen?
Should maintain most basic structure - have one centromere and two telomeres
What happens after mitosis of normal chromosomes?
Normal splitting
What happens after mitosis of dicentric chromosomes?
Break in chromosome loss, less viable
What happens after mitosis of ascentric chromosomes?
no pulling forces, missegregation or chromosome loss
What are unbalanced rearrangments?
Leads to change the gene number, can be caused by deletions and duplications, when they involve at least one gene
What are balanced rearrangements?
Does not lead to changed gene number, will be arrangements that change gene order, like inversions and reciprocal translocations
What is pseudodominance?
Recessive alleles uncovered by deletion will appear as if they are dominant, can lead to defects if deletion involves haploinsufficient genes
What are the most common chromosomal rearrangements in humans?
Translocation
Translocations can cause
New phenotypes
What are proto-oncogene?
When mutated acquires novel activity to promote cancer
What is Chromothripsis?
Genome chaos, generated clustered chromosome rearrangements are characteristic for tumor cells
What is non-disjunction?
The failure of homologs (at meiosis) or sister chromatids (at mitosis) to separate properly at opposite poles
What is a frameshift mutation?
The insertion or deletion of a nucleotide pair or pairs, causing a disruption of the translational reading frame
What is translocation?
The relocation of a chromosomal segment to a different position in the genome
What is an inversion?
A chromosomal mutation consisting of the removal of a chromosome segment, its rotation through 180°, and its reinsertion in the same location
What is a dicentric chromosome?
A chromosome with two centromeres
What is euploidy?
A complete chromosome set or an exact multiple of the haploid chromosome set
What is polyploidy?
A chromosomal complement with at least three complete sets of homologous chromosomes
