Biology 100 Unit 9 Flashcards
is the scientific study of heredity
genetics
is the transmission of traits from one generation to the next
heredity
was the first to study genetics. He did this by observing patterns of inhertance in pea plants
Gregor Mendel
Organisms are composed pf combination of many different
traits
Some traits are common and are referred to as ________________________ while others may be rare or unusual
wild type traits
The reason why we see such differences is because
individuals may possess variations of each gene
The overall appearance of an organism is called its ______________ it includes its physiology
phenotype
AN organism’s genetic makeup is called its ___________. It is all the organisms genes and their exact
genotype
genes exist at specific positions pn chromosomes called gene_____________
locus
mendel studied
garden
Pea plants have a variety of easily __________
observed traits
Pea plants ___________________
self fertilize
Medel ___________________ plants with different plants with different traits. He found true breeds/ pure breeds individuals and created ___________________
cross fertilized; hybrids
genes have different versions which we call
alleles
Alleles can be _____ or _____
dominant or recessive
Diploid organisms have _________ alleles for a gien gene
2
Each egg carries _________ and each sperm carries _____________ when them fuse 2 allels for creating a diploid organism
1 allele
A ___________ is a cross between organisms that differ in only 1 trait. In this example, the different trait amongst the parent plants is the color of the flower
monohybrid cross
____________ can be performed for multiple traits
monohybrid cross
An explanation of a monohybrid cross is a
punnett square
when eggs and sperm form allele pairs seperate from parent cells to make cells
law of independent assortment
The result of the law of independent assortment is that
each haploid gamet is unique and has only one allele of each gene
A chromosome pair consists of two
homologous chromosomes
if the alleles on two homologous chromosomes are identical
homozygous
if the alleles are different this is called
heterozygous
Example of a homozygous dominant
PP
Example of a homozygous recessive
pp
Example of a heterozygous
Pp
_______ looks at organisms with 2 traits of interest
dihybrids cross
because alleles assort independently of other alleles during gamete formation formation
the results in all possible combination
Mendel’s principles apply to all organisms including the inheritance of thousands of
human traits
to determine the patterns of inheritance among families genetics draw
pedigrees
these illustrate the history of a trait in a family
pedigrees
the human disease hypercholesterolemia is another example of
incomplete dominance
Blood type ______ is the recessive phenotype
O
__ and __ are two _______ alleles
A B Codominat
since most of these disorders are fairly rare we can conclude that they are ___________
recessive
is the dominat disorder known as dwarfism. This condition is found in heterozygotes
Achondroplasia
In dwarfism DD is a
leathal combination
Additional tests can reveal
- incomplete dominance
- multi-allelic inheritance
- peitropy
- polygenic inheritance
When F1 offspring have an 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
example of incomplete dominance
If you are homozygous for the A allele (IAIA) or are heterozygous (IAi) your blood type is
A
If you are homozygous for the B allele (IBIB) or are heterozygous (IBi) your blood type is
B
If you are heterozygous with both dominant alleles present, you have blood type
AB
blood group gene in humans is an Blood Group (Phenotype) Genotypes Carbohydrates Present on Red Blood Cells Carbohydrate A Carbohydrate B Carbohydrate A and Carbohydrate B Neither example for a IAIA gene with A or multiple alleles.
ABO
If a single gene affects more than one trait, this is called
pleiotropy
If two or more genes have combined effects on the phenotype, this is called polygenic inheritance this occurs because
more than 1 gene influences the phenotype expressed
In addition to genetics, there are many ________________ that help shape the phenotype.
environmental influences
Linked genes are located close together on a chromosome, therefore during crossing over (in Prophase I of Meiosis) they are
often inherited together
To determine how crossing over worked, scientists used the fruit fly
disophila melangaster
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 chromosome
This allows 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.
Males
Females
XY
XX
Genes located on 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 bindness
This disorder is linked to the X chromosome.
– It is characterized by a malfunction of light- sensitive cells in the eyes.
Another sex-linked disease is ____________, a blood- clotting disease.
hemophilid
