L4 (PART 2): CYCLES AND PATTERNS Flashcards
I’m Basic unit of heredity passed from one generation to the next.
Gene
Variant form of gene
Allele
Allele can be?
___
___
dominant;
recessive
Specific physical location of a gene
Locus
Combination of alleles
Genotype
Genotypes can be?
__
__
__
homozygous dominant;
heterozygous dominant;
homozygous recessive;
Expression of alleles
ex. blue eyes, brown eyes.
Phenotype
Study of how genes and traits are pass down from one generation to to the next.
Genetic
Created the 3 laws of inheritance
Gregor Mendel
What are the 3 laws of inheritance
Law of
Dominance;
Segregation;
Independent Assortment
Law of Inheritance:
“When dominant and recessive alleles are both present, the recessive allele is
masked or suppressed. Only one is dominant and will be expressed”
Law of dominance
Law of Inheritance:
“Two alleles of an individual separate with an equal probability into gametes.
In addition, two gametes (male and female) fuse to produce a zygote
Law of Segregation
Law of Inheritance:
“During gamete formation, alleles for one gene do not affect the alleles for another gene.”
Law of Independent of Assortment
Used to help solve genetic problems
Punnett Square
What are the 3 Non-Mendelian Genetics
Incomplete Dominance;
Codominance
Pleiotropy
Non-mendelian Genetics
Situation where neither allele is fully dominant over the other, resulting in a heterozygous phenotype that is intermediate between the two homozygous phenotypes. F
Example: in a flower species where red (RR) is completely dominant and white (WW) is recessive, a heterozygous individual (RW) may display pink flowers, which is an intermediate phenotype.
Incomplete Dominance
Non-mendelian Genetics
situation where neither allele is fully dominant over the other, resulting in a heterozygous phenotype that is intermediate between the two homozygous phenotypes.
Examples: in a flower species where red (RR) is completely dominant and white (WW) is recessive, a heterozygous individual (RW) may display pink flowers, which is an intermediate phenotype.
Partial Dominance
Non-mendelian Genetics
The The heterozygote has a phenotype intermediate of the two homozygotes
Incomplete Dominance
Non-mendelian Genetics
two alleles are fully
expressed in the
phenotype
example:
white horse + red horse =Roan horse (red and white hair are expressed equally)
Codominance
Non-mendelian Genetics
Example of this is ABO Blood Typing System
Codominance
Non-mendelian Genetics
A single gene that has a multiple effects on the phenotype
Pleiotropy
Polygenic Inheritance
individuals in a population show a wide range of phenotypes, rather than falling into distinct categories.
Continuous Variation
In continuous variation,
The __ the number of genes and
environmental factors that affect a trait,
the continuous the variation in
versions of that trait.
therefore, __ proportional.
greater;
more
directly
Environmental effects on phenotype:
Rabbit is homozygous for an allele
that specifies a heat-sensitive
version of an enzyme in melanin-producing pathway
Melanin is produced in cooler
areas of body
This is an example of effect of __ on phenotype.
Temperature
Environmental Effects on Phenotype:
In Hydrangea macrophylla, action of gene for floral color (pink to blue) is influenced
by ____—pH < 5.5, blue flowers;
soil pH >5.5, pink flowers
Add aluminum sulfate to lower soil pH;
add lime to increase pH; add sodium
carbonate, rainbow colored flowers;
white varieties stay white regardless of
soil pH
soil acidity
_____ genes located on the sex chromosomes, particularly the X and Y chromosomes in mammals. These genes exhibit patterns of inheritance that are influenced by the sex of the individual. In humans, sex-linked genes are often associated with traits or disorders that are more commonly expressed in one sex than the other.
Sex-Linked Genes
Sex-Linked Genes Example:
A serious X-linked recessive condition which is the
inability of the blood to clot because the gene
does not code for the necessary clotting agents
What condition is this?
Hemophilia A
Sex-Linked Genes Example:
Y-linked (Holandric) – genes found
only on the Y chromosome
– Relatively fewer compared with Xlinked
– Ex: presence of long hair in the
external ear (hypertrichosis of
pinnae)
– Will manifest only in males since
they are the ones with the Y
chromosome
What condition is this?
Hypertrichosis
Traits that can be expressed
genotypically in the homozygous or
heterozygous conditions but the
expression of dominance is affected by
the sex of the individual involved
Ex: male pattern baldness – dominant in
males in the homozygous or
heterozygous condition, but will only
manifest in females in the homozygous
condition
Sex-Influenced Genes
__ genes are located on autosomes (non-sex chromosomes) but are expressed differently depending on the sex of the individual.
These genes may be dominant or recessive, but their expression is influenced by sex hormones or other factors that differ between males and females.
As a result, the same genotype can produce different phenotypes in males and females.
Sex-influenced
An example of a __ is pattern baldness in humans. The gene associated with pattern baldness is located on an autosome, but its expression is influenced by hormones such as testosterone.
Baldness is more common and often more severe in males because they have higher levels of testosterone, which can trigger the expression of the baldness gene.
sex-influenced trait
In summary, __ are located on the sex chromosomes and show different inheritance patterns between males and females, while ___ are located on autosomes but are expressed differently depending on the sex of the individual.
sex-linked genes;
sex-influenced genes
Example of this is presence of long hair in the
external ear (hypertrichosis of
pinnae)
Will manifest only in males since
they are the ones with the Y
chromosome
Sex-Linked Genes
refers to the inheritance pattern of traits that are controlled by multiple genes, each contributing a small amount to the phenotype.
Unlike traits controlled by a single gene (monogenic traits), polygenic traits are influenced by the interaction of multiple genes, as well as environmental factors.
Polygenic Inheritance
Polygenic traits often result in a continuous range of phenotypes rather than distinct categories. This means that individuals can exhibit a wide spectrum of intermediate phenotypes, with no clear-cut boundaries between them.
Examples of polygenic traits with __ include height, skin color, and intelligence.
continuous variation
