Shared Flashcard Set

Details

Chapter 11
The Basic Principles of Heredity
44
Biology
Undergraduate 1
03/05/2010

Additional Biology Flashcards

 


 

Cards

Term
Genes
Definition
Informational units in chromosomes
Term
Locus
Definition
Site of a gene in the chromosome
Term
Alleles
Definition
-Different forms of a gene
-Same loci on homologous chromosomes
Term
Diploid Individuals
Definition
-Genes have pairs of alleles on homologous chromosomes
Term
Homozygous
Definition
Two identical alleles
Term
Heterozygous
Definition
Two different alleles
Term
Genetics
Definition
The study of inheritance
Term
Gregor Johann Mendel
Definition
-Austrian monk
-Naturalist
-Began the field of genetics
-Studied inheritance in mid-1800's
-Had no knowledge of
DNA
Chromosomes
Meiosis
Term
How did Mendel study inheritance?
Definition
-Used the scientific method
-Pisum Sativum(garden pea) was his experiment organism
-Used tweezers and a paint brush as only tools
Term
Mendel's Experiments
Definition
-Observed multiple generations of pea plants
-applied math analysis to his observations
-made powerful inferences
-first to perceive a set of principles that govern inheritance
Term
Mendel's Inferences
Definition
-The basic units of inheritance are material elements
-These elements come in pairs
-These elements retain their character through many generations
-Pairs of these elements separate during the formation of gametes
Term
What makes the pea plant perfect for Mendel's experiment?
Definition
-self pollinating
-fertilization is separate for each seed
-Germinates easily
-Quick development
-Produce many offspring
-Many different characteristics that you can physically see
Term
What traits did Mendel observe and manipulate?
Definition
-seed shape
-seed color
-pod shape
-pod color
-flower color
-flower position
-stem length
Term
What was the result of Mendel's experiment?
Definition
-Mendel came to understand that for each character, two traits exist.
-one trait is dominant, the other recessive
Term
Dominant Allele
Definition
-masks expression of a recessive allele
Term
Phenotype
Definition
-physical appearance
Term
Genotype
Definition
-Genetic makeup/constitution
Term
Describe Mendel's principle of segregation
Definition
-During meiosis paired alleles separate
-Gametes(haploid) have one allele per locus
-Members of a gene pair segregate from one another prior to gamete formation
Term
Describe Mendel's principle of independent assortment
Definition
-Alleles of different loci are distributed randomly into gametes
-Recombination produces new gene combos not present in parental generations
-members of different gene pairs assort randomly into gametes
Term
Monohybrid cross
Definition
-homozygous parents(P generation)
-Alleles different at one locus
Term
Dihybrid Cross
Definition
-Homozygous parents(P generation)
-Alleles differ at 2 loci
Probablility:
-9:3:3:1
Term
What are the 3 generations?
Definition
P generation:
-2 homozygous parents, 1 dominant, 1 recessive
F1 generation:
-1st generation of offspring
-heterozygous
F2 generation:
-cross of two F1 individuals
Term
Test Cross
Definition
-Between unknown genotype and a homozygous recessive
Term
How are Mendel's principles of segregation and independent assortment explained by scientists today?
Definition
Segregation:
-Homologous chromosomes separate during meiosis

Independent assortment:
-Random orientation of chromosomes in metaphase 1 of meiosis determines how chromosomes are distributed into haploid cells
Term
Genetic Ratios
Definition
-Expressed as probabilities

-Probability:
expressed as fraction or decimal fraction
-favorable events divided by total events

-Range from 0(impossible) to 1(certain)
Term
The Product Rule
Definition
-The probability of two independent events occuring together:
Multiply the probabilities of each event occuring separately
Term
The Sum Rule
Definition
-The probability of an outcome that can be obtained in more than one way:
add the separate probabilites
Term
Linkage
Definition
Linked genes:
-Groups of genes on the same chromosome tend to be inherited together

Two loci linked close together:
-On same pair of homologous chromosomes independent assortment does not apply
Term
Recombination of linked genes
Definition
-Can occur from crossing over in meiotic prophase I
Term
Crossing-over
Definition
-breaking and rejoining of homologous chromatids
Term
Linkage map
Definition
To construct:
-measure the frequency of recombination between linked genes
Term
What is a two-point test cross, and what does it do?
Definition
Cross between:
-1 individual heterozygous at both loci and
-1 individual homozygous recessive.

It distinguishes between independent assortment and linked genes

Linkage results:
-excess of parental-type offspring and deficiency of recombinant-type offspring
Term
XX Chromosomes
Definition
Female:
X-bearing egg
X-bearing sperm
Term
XY Chromosomes
Definition
Male:
X-bearing egg
Y-bearing sperm
Y chromosomes determines male sex
Term
What are X-linked genes?
Definition
-X-linked genes are sex-linked.
X chromosome:
-important for males and females.
-Males receive all X-linked genes from mother
-Females receive x-linked genes from both parents
Example X-linked color blindness:
-Female is carrier
Term
Dosage Compensation
Definition
-In female mammals
-Only one of two X chromosomes is expressed in each cell
-Inactive X becomes Barr body
Term
Pleiotropy
Definition
-Ability of one gene to have several effects on different characters
-Usually due to single cause such as a defective enzyme
Term
Multiple Genes
Definition
-Alleles of many loci may interact to affect the phenotypic expression of a single character
Term
Incomplete dominance
Definition
-A condition in which neither member of a pair of contrasting alleles is completely expressed when the other is present.
Term
Codominance
Definition
-Condition in which two alleles of a locus are expressed in a heterozygote.
Term
Multiple Alleles
Definition
-Three or more alleles of a single locus (in a population), such as the alleles governing the ABO series of blood types
-Diploid individual has any two alleles
-Haploid individual or gamete has only one allele
Term
Epistasis
Definition
-An allele of one locus can mask the expression of alleles of a different locus
Ex:
-Black, yellow, chocolate labs
Term
Polygenic Inheritance
Definition
-Multiple independent pairs of genes may have similar and additive effects on the phenotype

-Inheritance in which several independently assorting or loosely linked nonallelic genes modify the intensity of a trait or contribute to the phenotype in additive fashion.

Ex:
-Skin color, human height
Term
Norm of Reaction
Definition
- A range of phenotypic possibilities from a single genotype under different environmental conditions

Ex Height:
-genes affect height, set norm of reaction limits for height
-modified by environmental conditions such as diet and general health within the norm of reaction
Supporting users have an ad free experience!