The Chromosomal Basis of Inheritance Flashcards
Mutations
Heritable changes in genetic information
How many main groups of mutations are there
2
What are the two main groups of mutations
Chromosomal mutations and gene mutations
Gene mutations
Changes/mistakes in a single gene
What is a synonym of gene mutations
Point mutations
Point Mutations
Genie mutations that involves changes in one or a few nucleotides
How many types of gene mutations are there
3
What are the three types of gene mutations
Substitutions deletions and insertions
When did gene mutations generally occur
Replication
Substitutions
Mutation in which one bases change to another base usually affects only one amino acid or has no effect at all
What is an example of a Disease caused by a substitution
Sickle cell disease
What is sickle cell disease caused by
One mismatched base which changes one amino acid
Insertions
Point mutations in which one base is added to the sequence these are generally worse because they change all of the amino acids formed by groups of three after the base that is inserted
Deletions
Point mutations in which one bases taken away from the sequence
What are insertions and deletions also known as
Frameshift mutations
Frameshift mutation
Mutations that shift the reading frame of the genetic message
these alter every amino acid to follow the point of mutation and therefore proteins
Chromosomal mutations
Mutations that involve changes in the number location and structure of chromosomes they can also affect the number of copies of genes
Where do chromosomal mutations usually occur
Crossing over in prophase
How many types of chromosomal mutations are there
4
What are the four types of chromosomal mutations
Deletions duplications inversions translocation
Deletions (chromosomal mutations)
Loss of all or part of a chromosome (one or more genes)
Duplication
Duplication of all or part of a chromosome (one or more genes)
Inversion
Has the same amount of genes but they are in a different order (can be portion or the whole chromosome)
Translocation
When a part of a chromosome switches (in crossing over) with a non-homologous chromosome
How are mutations beneficial
Mutations are key to evolution and are a source of genetic variation
How can genetic material be altered
Buy natural events or artificial means
How can mutations affect organisms
Mutations can be beneficial harmful or helpful and can also affect a species or even a whole ecosystem
Mutagens
Chemical or physical agents in the environment that cause mutations generally these are not good or bad
Polyploidy
When an organism has more than 2 sets of chromosmes
What can polyploidy result in
Triploid (3n) or tetraploid organisms (4n) etc. etc.
What is polyploidy a result of
Usually a result of not separating chromosomes in meiosis or no cytokinesis
Is polyploidy beneficial or harmful
Harmful to animals but beneficial to plants because it makes them stronger
Chromosome Theory of Inheritance
genes are located at specific positions (loci) on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns
Thomas Hunt Morgan
Analyzed the behavior of two alleles of a fruit fly eye color gene
what did Thomas Hunt morgan mate
Morgan mated a wild-type (red-eyed) female with a mutant white eyed male fruit flies
Drosophila melanogaster
common fruit fly
why did Morgan use fruit flies
bc each mating produces hundreds of offsprings and they have the same chromosomes as humans
sex linked genes
A gene located on either sex chromosome
which sex chromosome has most of the genes on it and why
X bc both males and females have it
who is more likely to exhibit sex linked traits and why
males because they only need one copy of the gene bc they only have one of each chromosome so even if its recessive there’s not another chromosome to cancel out the other one
Who determines the gender of a child
father
In a Z-W chromosome system who determines the gender of the child
mother
In a X-O chromosome system who determines the gender of the child
the male
In a X-O chromosome system what is the genotype of the male and the female
male:XO
female:XX
In a Z-W system what is the gender of the male and the female?
male: ZZ
female: ZW
In a halpoid diploid system which is female and which is male
male: haploid
female: diploid
what kind of chromosome system do bees have
haploid diploid
sex linked recessive disorders are more common in what
in males
Parents pass down the genes for red-green color vision deficiency through the ___ chromosome
X
If a sex linked disorder is found on the x chromosome can boys get them from their dads
no bc they only pass down the Y
Parents pass down the genes for Duchenne muscular dystrophy through the ___ chromosome
x
Parents pass down the genes for hemophilia through the ___ chromosome
X
Duchenne muscular dystrophy
A human genetic disease caused by a sex-linked recessive allele; characterized by progressive weakening and loss of muscle tissue
Hemophilia
absence of one or more blood-clotting proteins; characterized by excessive bleeding following injury
X inactivation in female mammals
one of the x chromosomes of females deactivates in embryogenesis
Barr body
super dense inactive X chromosome
Does the process of X inactivation happen to a specific X chromosome and if so which one
no its random
Where is the Barr Body located
nuclear envelope
XIST stands for
X-inactive specific transcript
how do x chromosomes turn into barr bodies
By the processes of methylation (of the histones), the X chromosome barr body turns itself off, codes for methyl groups to cover chromosomes (RNA polymerase covers, turning off genes)
X-inactive specific transcript
linked genes
genes located close enough together on a chromosome that they tend to be inherited togethter
Nondisjunction
An error in meiosis or mitosis in which members of a pair of homologous chromosomes or a pair of homologous chromosomes or a pair of sister chromatids fail to separate properly from each other
what types of disorders does nondusjunction cause
aneuploidy, trisomy, monosomy, polyploidy
Aneuploidy
abnormal # of chromosomes
Trisomy
diploid cell with 3 copies of a chromosomes
Monosomy
when a diploid cell has 1 chromosome instead of 2
Down Syndrome
A human genetic disease usally caused by the presence of an extra chromosme 21; characterized by developmental delays and heart and other defeats that are generally treatable or non-life-threat
Klinefelter Syndrome genotype
XXY
Klinefelter Syndrome characteristics
Extra X chromosome; sterility, big boobies small dick
Superman disorder genotype
XYY
Superman disorder
lots of testosterone js ore male type shi
XXX Females
Extra X chromosmes; no unusal physical features, risk for learning disabilites, but fertile
Turner Syndrome genotype
XO
Turner Syndrome Characteristics
Only known viable monosomy in humans, phenotypically female, sterile because their sex organs do not mature. Normal inteligence
Cri-du-chat cause
deletion in chromosmes 5
Cri-du-Chat
a child born with the deletion is severely intellectually disabled, with unusual facial features and has a cry like a distressed cat. infants die in infancy or early childhood
Chronic Myelogenous Leukemia caused by
the exchange of a large portion of chromosome 22 with a fragment of chromosme 9
Chronic Myelogenous Leukemia characteristics
cancer of white blood cells
What do translocation, inversion, duplication, and deletion of the chromosme often lead to
abortion
in what stage of meiosis and mitosis does nondisjunction occur in
anaphase
mosaicism
when (like the cat) you can see a bunch of different colors because in different cells different x chromosomes are inactivated and therefore you see different traits expressed in different areas
nondisjunction in meios will affect what types of cells
zygotes
nondisjunction in mitosis will affect what types of cells
somatic cells
genomic imprinting is dependent on what
which parents
genomic imprinting
moms and dads imprint chromosomes differently (even if its the same gene) which affects expression in children differently because the parents with methylate chromosomes at different spots in a gene
prader Willi Syndrome and angelman syndrome cause
deletion of chromosome 15
re-imprinting in offspring
Duirng methylation imprint chromosomes to make all your genes when making your own gametes
methylation
Methyl (-CH3) groups are added to the cytosine nucleotides of one of the alleles. Methylation can silence or activate the expression of an allele
myopathy
disorder of mitochondria in which not a lot of ATP is produced so there can be a range of bad effects for different people which can include lethargy, weakness, etc.
genetic recombination
General term for the production of offspring with combinations of traits that differ from those found in other parents
linked genes are..
more likely to get inherited together because they are closer together on chromosomes
if the recomibination frequency is lower describe the location of genes on a chromosome relative to one another
they are closer together and harder to separate
if the recomibination frequency is higher describe the location of genes on a chromosome relative to one another
they are further apart and easier to separate
recombination frequency
measure of how often genetic material is exchanged between chromosomes during meiosis
what is the recombination frequency of 2 genes on different chromosomes and why
50% bc when genes are far from each other there’s lots of possibilities and recombination happens 2-3 times so it could go back and forth
if there is a higher recombination frequency what does that mean
there is a higher chance for recombination bc there’s more area to cross over
what is the significance of Morgan’s experiment with gray and normal wings crossed with black vistigial wings
the numbers were completely different from mendelian numbers and led to the discovery of linked genes
what is the significance of Morgan’s experiment with red and white eyes
they were different from mendelian numbers and led to the discovery of sex linked genes bc mostly only males had red eyes
linkage map
map that shows how close genes are and how likely they are to be inherited together
if 2 genes are on the same chromosomes what is the chance of them being inherited and why
50 bc of crossing over
cytological map
More detailed locus of gene; done by staining patterns on chromosome
if there is a higher frequency is the distance between the chromosomes bigger or smaller
bigger
map units
a unit of measurement of the distance between genes
one map unit is equal to a ___ recombination frequency
1%
