GENETICS Lecture 7a+7b Flashcards
THE FOUNDER OF GENETICS?
Gregor mendel(1822-1884)
What is genetics?
branch of biology concerned with heredity and variation of inherited characteristics.
who is the father of medicine and what was his idea of genetics?
HIPPOCRATES (500-400b.c)
Pan genesis- particles called pangenes travel from each part of an organism’s body to the egg/sperm, and are then passed to the offspring.
what was Aristotle’s perspective about Hippocrates Pan genesis?
rather than the particles of the organs itself, the formers inherited characteristics were formed from blood.
According to Aristotle, Blood’s __________ had the capacity to produce offspring of the same form, not because it already contained all parts in miniature.
VITAL HEAT
What is the “Theory of Epigenesis” and who proposed it?
WILLIAM HARVEY (1578-1657),ENGLISH ANATOMIST
An organism is derived from substances present in the egg, which differentiate into adult structure during embryonic development.
What is the “Atomic theory” and who proposed it?
JOHN DALTON 1808
All matter is composed of small invisible units called atoms.
What is “Germ(cel) Theory” and who proposed it?
LOUIS PASTEUR (1822-1895)
All organism are composed of basic visible units called cells, which are derived from pre-existing cells.
What is the “FIXITY OF SPECIES” and who proposed it?
CAROLUS LINNAEUS (1707-1778)
member of species can only give rise to other member of species, thus implying that all species are independently created.
What do u mean by “The inheritance of acquired characteristics” and who proposed it?
Jean-Baptiste Lamarck (1744-1829)
that traits acquired by an organism during its lifetime can be passed on to its offspring..
What the “the theory of origin of species” and who proposed it?
CHARLES DARWIN (1809-1882)
EVOLUTION-Descent with modification
-Species change over time, give rise to new species and share a common ancestor.
what is the “Blending theory of Inheritance”?
Hereditary traits blend evenly in offspring, through mixing of the parent’s blood.
Offspring inherits the average of the parent’s characteristic value.
when did Gregor experimented with garden peas?
1860s
what were characters and traits for Mendel?
CHARACTER-variety of heritable characteristics-seed shape, flower colour
TRAITS-variation in a character-purple flower, white flower
what did Mendel establish about genes?
Characters are passed into offspring in the form of discrete hereditary factors, known as genes.
the principle of inheritance were first demonstrated by ______.
Gregor Johann Mendel
-1st scientist to effectively apply quantitive methods to the study of inheritance.
Two major discoveries of Mendel?
-PRINCIPLE OF SEGREGATION
-PRINCIPLE OF INDEPENDENT ASSORTMENT
WHAT ARE ALLELES?
alternative form of genes, which may have diff DNA sequence and may produce diff traits of a same character(white or purple flower)
DIPLOID?
Organism with 2 copy of each chromosomes
the two alleles of a gene in a diploid individual maybe ______ or ________.
identical or different
Mendel called the masking effect as ______.
Dominance
what 3 hypothesis are supported by Mendel’s crossed?
-one factor for each parent.
-one is dominant over the other.
-gene segregate,enter gametes singly.
NAME THE PRINCIPLES OF MENDEL FOR CHOOSING PEA PLANT FOR HIS EXPERIMENT?
-easily cultivated in garden
-many varieties- distinguishable traits
-diploid
-self pollinated in nature
-can be cross pollinated by hands, both self and cross pollination possible
PHENOTYPE?
Physical appearance of an organism-traits-appearance, development, biochemical and psychological properties, behaviour
GENOTYPE?
Genetic makeup of an organism
name the 3 factors that determining phenotype?
-Genotype
-epigenetic factors
-non- inherited environmentaal factors
Experiments to determine the pattern of inheritance of single traits are known as _____________.
MONOHYBRID CROSS
Varieties with the traits chosen by Mendel had _________.
True-breeding lines
Define true breeding line?
AKA pure breeding
when self fertilized, pass traits from one generation to another with little to no variation.
define cross(hybridization)?
cross fertilization of 2 diff species
Hybrid?
offspring of ParentS “P” of 2 diff species
F1 generation?
offspring resulting from cross of parents
F1- first filial generation
F2 generation?
next gen (offspring) of plants from self pollination of F1*F1
what was the observation of Mendel in a MONOHYBRID CROSS for flower color?
1.no blending observed in F1
2.produced both purple and white-3:1
what were the propositions made my Mendel after observing all 7 traits of pea plants?
-for each trait their is a pair(alleles) of heritable factor (genes) in each parent.
-gamete formation- 2 factors of trait separate - 1 is passed onto a gamete.
-during fertilization, each parent contributes 1 factor for a trait-offspring (pair of factors)
-cross b/w individual with diff traits of a pair-both present, one masked by other
Homozygous?
true breeding - 2 identical allele- PP or pp.
Heterozygous?
diff allele for given characteristic- Pp
Hemizygous?
condition in which only 1 copy of a gene or DNA sequence present in a diploid cell.
what is a Punnett square and whom is it named after?
A tool to predict the probability of possible genotypes of offspring.
-“REGINALD CRUNDALL PUNNETT”-1875-1967 British biologist/geneticist
Test cross?
cross of an individual with unknown genotype(either heterozygous or homozygous)for a particular characteristic with a homozygous recessive individual for the same charcteristic.
What is Mendel’s first law?
LAW OF SEGREGATION
When any individual produces gametes, the alleles seperate so that each pair of gamete receive only one allele.
_________ is used by geneticists as a standard test to determine whether an individual with a dominant trait is heterozygous or homozygous.
Testcross
DIHYBRID?
A zygote produced from a cross that involves 2 characters. as in seed shape and seed color
what was the reason behind Mendel performing dihybrid cross?
to see if the 2 traits of parent are passed on together on gametes or whether they segregate independtly.
In Mendel’s 2 trait passed on together, then ______ type of gametes formed on the hypothesis of linked assortment are?(YyRr)
2
YR,yr
according to hypothesis of independent assortment (2nd possibility considered by Mendel) ______ types of gametes could be formed in equal numbers?
(YyRr)
4
YR,yr,Yr,yR
1:1:1:1-PHENOTYPE
9:3:3:1-GENOTYPE
Two traits segregate ______ of each other during gamete formation.
Independent
In various combinations of dihybrids traits, Mendel observed that each of 2 traits produced a ______ ratio of phenotypes in the F2 and 2 trait combination always showed a ________ ratio.
3:1
9:3:3:1
What is Mendel’s Second law?
Law of independent assortment
-Alleles of 2 or more diff genes get sorted into gametes independently of each other
Mendel’s _____ completely confirmed his hypothesis.
Testcrosses
Describe chromosome theory of inheritance?
Sutton-Genes and their alleles are carried on a chromosome.
the particular site on a chromosome at which gene is located is called the ________.
locus
Name some variation of Mendel’ principles.
-incomplete dominance
-Co dominance
-Multiple alleles
-pleiotropy
-epistasis
-polygenic inheritance
INCOMPLETE DOMINANCE?
Occurs when the effects of recessive alleles can be detected to some extent in heterozygotes.
What does incomplete dominance results in ?
3rd phenotype-expressed phenotype is a combination of phenotypes of both alleles.
eg red+white=red, white , pink flower in F2 generation.
CO DOMINANCE?
2 diff phenotypes both make significant contributions to the appearance of third phenotype (both parental traits appear together).
The ______ blood type does not affect blood transfusions and is frequently used in initial test to determine the _______ of a child.
MN
Paternity
Multiple alleles?
Occurrence of a gene that exists as three or more alleles in a population.
Pleiotropy?
the determination of more than one character by a single gene.
which protein in RBCs carry oxygen throughout the body.
Haemoglobin
Epistasis?
interaction of multiple genes where the effect of one gene influences the expression of another gene’s phenotype.
______ occurs when 2 or more diff gene loci contribute to the same phenotype.
epistasis
Polygenic inheritance?
combined effects of multiple genes shape the observed phenotypes.
(additive effect of 2 or more diff gene loci on a single phenotype.)
additive effect of 2 or more diff gene loci on a single phenotype is known as _______ and the in additive effect is known as _________.
Additive-polygenic inheritance
in additive- epistasis
skin color in humans is an example of ________ inheritance.
polygenic
how does behaviour of chromosomes during meiosis accounts for Mendel’s principle of inheritance patterns?
1.diploid individual has 2 sets of homologous chromosomes.
2.2 chromosomes=2 alleles (same or diff) at same positions
3.each set comes from male or female
4.when any individual produce gametes-alleles separate- each gamete gets one allele from the pair
genes are located on ___________.
chromosomes
what is a gene locus
site on chromosome where gene is found
genes can exist in 2 or more _______ alleles
2 or more
recombination of unlinked genes follow which of the Mendel’s principle ______________________?
the chromosome basis of allele segregation, independent assortment
what are linked genes?
genes that are located close together
during meiosis close localized gene tend to be ________ to a gamete
passed together
define crossing over
the exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring during the prophase of meiosis 1.
________ accounts for the recombinant gamete formation and recombines ______ genes into assortment of alleles not found in ________.
crossing over
linked genes
parents
who first demonstrated the effects of crossing over on fruit fly, ________ recombination.
T.H. Morgan (1900s)
phenotype
scientific name for fruit fly is ________
Drosophila melanogaster
during _______ of meiosis I, homologous chromosome synapse to form ________ and ______ occurs
prophase
bivalent
crossing over occurs
how to calculate recombination frequency
recombinants/# total offspring *100
use of segregation ratios to predict ____________.
percentage of recombinants or recombinant frequencies
using segregation ratios to predict ______, _____ maps could be developed to help determine the position of diff ________ on the same chromosome.
recombinant frequencies
linkage maps
genes or loci
who created the first linkage map and using what as a measurement?
using recombinant frequency as measurement, Alfred H. Sturtevant created 1 linkage map showing 5 genes on chromosome 2 of Drosophilia.
what is the unit of linkage map and what is it equivalent to?
Map unit (mu)
equivalent to a recombinant offspring frequency of 1%
the map unit is also called _______ in honour of Morgon’s discovery of ___________ and _______-.
centimorgan (cM)
linkage and recombination
what theory was confirmer by Morgan and his colleagues?
chromosomal theory of inheritance
that genes are located on chromosomes, and the inheritance patterns of traits can be explained by the behavior of chromosomes during cell division.
mendel’s theory of dominance and recessive variants could not account for _________ in observed 1:1 ratio.
inheritance of sex
what determine the sex of the chromosome?
one of the chromosomes-sex chromosomes
what about chromosome distribution in insects such as flies and grasshoppers?
female-XX
Male-only X, Y absent—designated as XO
what are the sex chromosomes in birds and fishes
male is (XX)called ZZ
female has (XY)called ZW
who determine the sex of offspring in birds and fishes?
female with (ZW) XY chromosome, whereas male have XX (ZZ)
what about sex determination in ants and bees?
Sex is determined by chromosome number,
female develop from fertilized egg(diploid)
male develop from unfertilized egg(haploid)
________ is any chromosome that is not sex chromosome.
autosome
human individuals with abnormal sex chromosomes could be physically normal but _______.
sterile
what is turner syndrome
XO individuals-partial or complete absence of one of the X chromosomes
females, could be physically moderately abnormal
mentally normal
sterile
who are individuals with XXY chromosome
males, could be physical normal but always sterile, small testicles
XXY are ______ with _________ syndrome
males, klinefelter syndrome
XYY which occurs -____ in 1000 _____ births show clinical phenotype.and have normal _________ and _______. and is known as __________ syndrome
1 in 1000 male
sexual development, normal fertility
Jacobs syndorme
many of the genes on sex chromosomes are for ________ traits.
non-sexual
Y chromosome contains less than ______ genes, among them there are _______ dominants, however X chromosome contains over _______ genes.
200 genes
maleness dominants
1000 genes
several imp human diseases are inherited as _________ recessive, give some examples and which sex has more frequency to get them.
X-linked recessive
ex-muscular dystrophy, red-green colour blindness and hemophilia
men>women
define hemophilia
mostly inherited genetic disorder that impairs the body’s ability to make blood clots, because it lack sufficient blood clotting proteins(clotting factors)
define extranuclear inheritance
aka cytoplasmic inheritance
transmission of genetic material located outside the cell nucleus, notably in mitochondria or chloroplasts.
maternal inheritance related extranuclear inheritance?
- mitochondrial and chloroplast genome that affect offspring’s phenotype.
2.maternal genes products that influence early development - epigenetic
3.infectious particles- able to make horizontal gene transfer
define epigenetic
study of change of organism caused by modification of gene expression rather than alteration of genetic code itself.
________ is energy converting organelle of eukaryotes evolved from _________ that were engulfed by primitive _______ and developed a _______ relationship (________) with them about 1.5*10e9 years ago.
mitochondria
prokaryotes(proteobacteria)
eukaryotic cells
symbiotic(endosymbiosis)
the human mitochondrial genome contains _______ bp and encodes ____ genes
16,569base pairs
37 genes
extranuclear inheritance in mitochondria?
maternal inheritance
high mutation rate
threshold effect for disease
age-related mutations
where are chloroplast present and what process takes place in it
land plants, algae and some protists
photosynthesis
where is the origination of chloroplasts believed from
cyanobacteria through endosymbiosis
how many unique genes are present in land plant chloroplasts?
110-120
-maternal inheritance
define cytoplasmic inheritance and who discovered it?
the transmission of genes that occur outside the nucleus
Carl Erich Correns (1864-1933)
what was correns experiment about
maternal inheritance in the four o clock plant (Mirabilis Jalapa)
the non mendelian inheritance pattern discovered by correns was later traced to a gene named ________ that codes for a small_________ required for proper assembly of chloroplast ribosomes.
iojap
protein(chloroplastic)
what are the 3 different types of pathogens that can deliver genetic material to eukaryotic nuclei?(horizontal gene transfer)
1.viruses(ssDNA,dsDNA,RNA)
2.prokaryote Agrobacterium tumefaciens(ssDNA)
3.intercellular eukaryotic parasit-Trypanasoma Cruzi(minicircle DNA)
example of an infectious particles in plasmids ?
agrobacterium tumefaciens- bacterial pathogen
crown gall on a rose stem
what is a ti plasmid
a tumor inducing plasmid found in pathogenic species of agrobacterium
where does the transfer, integration and expression T-DNA in an infected plant takes place?
Ti Plasmid (Tumor inducing plasmid)
what results in production of grown gall tumours?
transfer, integration and expression of T-DNA (Tumour DNA) in Ti plasmid In an infected plant that results in the production of crown gall tumours.
