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Definition
| Informational units in chromosomes |
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| Site of a gene in the chromosome |
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-Different forms of a gene
-Same loci on homologous chromosomes |
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| -Genes have pairs of alleles on homologous chromosomes |
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-Austrian monk
-Naturalist
-Began the field of genetics
-Studied inheritance in mid-1800's
-Had no knowledge of
DNA
Chromosomes
Meiosis |
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Term
| How did Mendel study inheritance? |
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Definition
-Used the scientific method
-Pisum Sativum(garden pea) was his experiment organism
-Used tweezers and a paint brush as only tools |
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-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 |
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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 |
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| What makes the pea plant perfect for Mendel's experiment? |
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Definition
-self pollinating
-fertilization is separate for each seed
-Germinates easily
-Quick development
-Produce many offspring
-Many different characteristics that you can physically see |
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Term
| What traits did Mendel observe and manipulate? |
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Definition
-seed shape
-seed color
-pod shape
-pod color
-flower color
-flower position
-stem length |
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Term
| What was the result of Mendel's experiment? |
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Definition
-Mendel came to understand that for each character, two traits exist.
-one trait is dominant, the other recessive |
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Definition
| -masks expression of a recessive allele |
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| -Genetic makeup/constitution |
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| Describe Mendel's principle of segregation |
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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 |
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Term
| Describe Mendel's principle of independent assortment |
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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 |
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Term
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Definition
-homozygous parents(P generation)
-Alleles different at one locus |
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Term
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Definition
-Homozygous parents(P generation)
-Alleles differ at 2 loci
Probablility:
-9:3:3:1 |
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Term
| What are the 3 generations? |
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Definition
P generation:
-2 homozygous parents, 1 dominant, 1 recessive
F1 generation:
-1st generation of offspring
-heterozygous
F2 generation:
-cross of two F1 individuals |
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Term
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Definition
| -Between unknown genotype and a homozygous recessive |
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Term
| How are Mendel's principles of segregation and independent assortment explained by scientists today? |
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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 |
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Definition
-Expressed as probabilities
-Probability:
expressed as fraction or decimal fraction
-favorable events divided by total events
-Range from 0(impossible) to 1(certain) |
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Definition
-The probability of two independent events occuring together:
Multiply the probabilities of each event occuring separately |
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Definition
-The probability of an outcome that can be obtained in more than one way:
add the separate probabilites |
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Term
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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 |
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Term
| Recombination of linked genes |
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Definition
| -Can occur from crossing over in meiotic prophase I |
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Definition
| -breaking and rejoining of homologous chromatids |
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Definition
To construct:
-measure the frequency of recombination between linked genes |
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Term
| What is a two-point test cross, and what does it do? |
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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 |
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Definition
Female:
X-bearing egg
X-bearing sperm |
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Male:
X-bearing egg
Y-bearing sperm
Y chromosomes determines male sex |
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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 |
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Term
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Definition
-In female mammals
-Only one of two X chromosomes is expressed in each cell
-Inactive X becomes Barr body |
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Definition
-Ability of one gene to have several effects on different characters
-Usually due to single cause such as a defective enzyme |
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Term
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Definition
| -Alleles of many loci may interact to affect the phenotypic expression of a single character |
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Term
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Definition
| -A condition in which neither member of a pair of contrasting alleles is completely expressed when the other is present. |
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Definition
| -Condition in which two alleles of a locus are expressed in a heterozygote. |
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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 |
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Definition
-An allele of one locus can mask the expression of alleles of a different locus
Ex:
-Black, yellow, chocolate labs |
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Term
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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 |
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Term
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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 |
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