Chapter 14 & 15 Flashcards
Define alleles
different versions of genes
define genes
genetic information that codes for a specific trait
define traits
a specific characteristic of an individual
Define true breeding
homozygous dominant → AA
homozygous recessive → Aa
Define heterozygous
Aa
Define phenotype
physical expression of a gene
Define genotype
the genetic makeup→ the combination of inherited allele
What are the four parts of Mendel’s Model
1.Alternate versions of genes → ALLELES
2.Organisms inherit two copies of a gene
3.Dominant Allele and Recessive Allele
4.Law of Segregation
Define Law of segregation
Two alleles will separate into two gamete cells
Define Law of Independent assortment
2 alleles will independently separate into two gamete cells
Define F2
cross between two individual from F1 generation
define a testcross
breeding of a unknown genotype with recessive homozygous
To find the genotype of a dominant phenotype
What are the steps to read a pedigree?
- Determine if the trait is dominant or recessive:
Dominant: will not skip a generation; one parent MUST have the trait
Recessive: neither parent is required to have the trait- heterozygous
2.Determine if the trait is autosomal or sex-lined
X-linked recessive= males are much more commonly affected than females
Autosomal traits: both males and females are equally likely to be affected
During what phases of meiosis will the law of segregation take place?
In Anaphase 1: the homologous chromosomes will separate into two gamete cells
In Anaphase 2: the sister chromatids will separate into two gamete cells
During what phases of meiosis does the law of independent assortment take place?
Anaphase 1- homologous chromosomes
Anaphase 2 sister chromatids
During metaphase 1 & 2 , alleles will independently orient on the metaphase plate
What is a wild type?
phenotype most commonly observed
w+
What is a mutant?
phenotype due to alleles that have changes
w
What are some sex-linked diseases?
Colorblindness, hemophilia, and duchenne’s muscular dystrophy
What is nondisjunction?
Homologous chromosomes do not move apart during during meiosis 1 & sister chromatids do not separate during meiosis 2;
can also affect autosomal chromosomes
What are some autosomal nondisjunction disorders?
trisomy 21(down syndrome)
Trisomy 18
Trisomy 13
In which chromosomes do autosomal nondisjunction disorders take place?
autosomes- 22 pairs
What do people with sex chromosome nondisjunction have trouble with?
childbearing
What are some sex chromosome nondisjunction disorders?
Kleinfelters, Turners
What is kleinfelters disorder?
XXY → male
Sterile; Some female body characteristics
Turners’ disorder
sterile; females; missing and X
X0
XYY characteristics
extra aggression→ Male; taller than average and normal sexual development
XXX characteristics
female- tall and slender; issues with personality & socialism: a difficulty with childbearing
What is the difference between mitochondria DNA inheritance and Nuclear DNA inheritance?
mitochondrial and chloroplast DNA inherited from the mother
Nuclear DNA can be inherited from mother and father
What is phenotypic plasticity?
effect of environment on phenotype
Phenotypic plasticity in hydrangea flowers and pH
Flower color→ soil pH
Acidic soil- low pH→ blue or lavender
Basic soil→ higher pH→ pink or red flowers
Phenotypic Plasticity- Carbon dioxide levels and stomate density
Low amounts of CO2→ more stomates
High amounts of CO2→ fewer stomates
Phenotypic Plasticity- of Siamese cats
tyrosinase= catalyzes first step of melanin production
Temperature above 33C- inactive- no pigment
Temperature below 33C- active- pigment present
Phenotypic plasticity- snow shoe hare
Ice pack- too cold; enzyme for white coat is not activated
Phenotypic Plasticity- butterflying wings
Warm temperatures of wet season= large and bright eyespots
Cool temperatures in dry season= dull an dsmall eyespots
what are linked genes
genes that are very close together. Due to their closeness, they cannot cross over and crossing over results in recombination. Thus, not many recominants were formed.
exception to medelian genetics
define parentals
offspring with the same genotype as the parents
define recombinants
offspring that are a mix of their parents
recombination frequency of 50% or greater
genes are either are on different chromosomes or are very far apart from each other on the same chromosome such that they will assort independently
recombination frequency less than 50%
genes are closer together and linked
when would you reject null hypothesis?
when chi square value is greater
incomplete dominance
when two alleles express their traits in a blended manner
co-dominance
mixture of two dominant alleles
