Chapter 9 Flashcards
The scientific study of heredity.
Genetics
The transmission of traits from one generation to the next.
Heredity
Who was the first to study genetics?
Gregor Mendel
Gregor Mendel
was the first to study genetics, and did this by observing patterns of inheritance in pea plants
Organisms are composed of combination of many different _____.
traits
Some traits are common, and are referred to as ____________, while others may be rare or unusual.
wild type trait
The reason why we see such differences is because____________________________.
individuals may posses variation of each gene
Offspring inherit these genetic variations from their parents, incorporating their parents genetic information in the offspring ________.
Genome
The overall appearance of an organism is called its __________.
Phenotype
The phenotype includes.
all visible characteristics of an organism, including its physiology
An organisms genetic makeup is called.
Genotype
The genotype is all of the organisms.
genes and their exact DNA composition
Genes exit at specific position on the chromosomes called?
Gene locus (pl.loci)
Mendal studied __________.
Garden peas
Pea plants
have variety of easily observed traits
they are easily manipulated
they are normally self fertillized
Mendals experimental treatments consisted of ____-______ plants with different traits.
Cross-fertilizing
Mendals found true-breeding (purebred) individuals and crossed them to create________.
hybrids
Genes have different versions, which we call _____.
Alleles
Diploid organisms have __ pair (_) alleles for a given gene.
1
2
Each egg carries __ copy of each _____. and each sperm also carriers____ copy of each _____.
1 allele
1 allele
Once sperm and egg fuse, the newly fertilized egg (zygote) has 2 copies of each allele and is therefore called?
Diploid
What is a diploid?
has 2 copies of each allele. these copies can be identical or different verison of each allele
If an allele is different what happens?
the dominant allele masks the the recessive allele and is expressed.
A ________ is a cross between organisms that differ in only 1 trait.
Monohybrid cross
An explanation of a monohybrid cross using a __________.
punnet square
a upper case letter is used to express what?
dominant traits
When eggs and sperm form, allele pairs separate from the parent cells to make _________.
haploid cells
What is the law of independent assortment?
Alleles also typically separate independently of other alleles.
A chromosome pair consist of two__________.
Homologous chromosomes
if the alleles on two homologous chromosomes are identical this is called_________.
homozygous
if the alleles are different this is called________.
Heterozygous
An example of homozygous recessive.
pp
example of homozygous dominant
PP
Example of heterozygous
Pp
A_________ looks at organisms with an organism with 2 traits of interest(crossing 2 traits at once)
dihybrid cross
Because alleles assort independently of other alleles during gamate formation,
this results in all possible combination
Mendels principles apply to all organisms, including the inhertiance of thousands of ________.
human traits
To determine the pattern of inheritance among families, geneticists draw__________.
pedigrees.
these illustrate the history of a trait in a family
pedigree
since most of these genetic disorders are fairly rare, we can conclude that they are __________
recessive
______________ is dominant disorder known as dwarfism.
Achondroplasia
Dwarfism is found in _____________.
heterozygotes
in Dwarfism with DD is a ____________.
lethal combination
When F1 offspring have appearance is an intermediate between two extreme parental phenotypes, this is the result of allelic __________________.
incomplete dominance
The human disease hypercholesterolemia is another example of
incomplete dominance
Blood type O is the
recessive phenotype
A and B are two _________alleles.
dominance
If you are homozygous for the A (IAIA) allele or are heterozygous (IAi) you blood type is __.
A
If you are homozygous for the B (IBIB) allele or are heterozygous (IBi) your blood type is____.
B
If you are heterozygous with both dominant alleles present you have blood type___.
AB
If a single gene affect more than one trait, this is called__________.
Pleiotrophy
If two or more genes have combined effects on the phenotype, this is called____________.
polygenic inheritance
Polygenic inheritance occurs because_______________________________.
more then 1 gene influence the phenotype expressed.
Linked genes are located close together on a chromosome, therefore during crossing over they are__________________.
often linked together
To determine how crossing over worked, scientist used the fruit fly ___________________.
Drosophila melanogaster
Using Drosophila, frequencies of gene inheritance (from crossing over) were determined. Based the frequent genes were inherited together, the more likely they are located _______________________________.
closer together on the same chromosomes
This allowed us to determine the order and spacing of genes on a chromosome, resulting in a ___________.
linkage map
Among the chromosome pairs of organisms, one pair may be the one carrying the genes to determine the sex of an individual these are called _______________.
sex chromosomes
humans have an ____ sex determination system.
XY
males are___.
XY
females are ____.
XX
genes located on the sex chromosomes are called_________________.
Sex-linked genes
the inheritance of ________________ in the fruit fly illustrates an X-linked recessive trait in the fruit fly drosophila melanoganaster.
white eye color
Among humans, a common type of sex-linked disorder is ________________________.
red-green color blindness
red-green color blindness is linked to the ___ chromosome.
X
Another sex-linked disease is ________ a bloodclotting disease.
Hemophilia
