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Genotype
the particular genetic makeup of an individual
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Phenotype
The visable measureable features of an individual
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Chromosome
a single, large DNA molecule wrapped around proteins (histones); located in the nuclei of most eukaryotic cells
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Sister Chromatids
- one of the two identical DNA molecules that make up a duplicated chromosome following DNA replication
- connected at a region of the chromosome known as the centromere
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Homologous chromosomes
- Same gene different alleles
- The two copies of each chromosome in a diploid cell. one chromosome in the pair is inherited from the mother, the other is inherited from the father
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How are the X and Y chromosomes different from homologous chromosomes?
Genes located on the X and Y chromosome in males do not have a second copy
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What are alleles?
Alternative versions of the same gene that have different nucleotide sequences
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Diploid
- having two copies of every chromosome
- sex cells or gametes
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Haploid
- Having only one copy of every chromosome
- somatic cells (non-reproductive cells)
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Autosomes
paired chromosomes present in both males and females; all chromosomes except the X and Y chromosomes
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Sex Chromosomes
- Paired chromosomes that differ between male and female
- XX= Female
- XY= Male
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In humans, does the male or female determine the sex of the child?
Male
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Heterozygous
Having two different alleles of a given gene
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Homozygous
Having two identical alleles of the same gene
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Dominant
An allele that can mask the presence of a recessive allele
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Recessive
an allele that reveals itself itself in the phenotype only if the organism has two copies of that allele
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What is the genotype of a person who is heterozygous dominant?
AA
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***What are the two major sources by which genetic variation is introduced into offspring?
- -mutation
- -chromosomes passed down
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Crossing over
- Homologousmaternal and paternal chromosomes pair up and swap genetic information. Maternal chromosomes actually contain segments from paternal chromosomes and vice versa
- Meiosis I
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Independent assortment
- Alleles of different genes are distributed independently of one another, not as a package. A unique combination of maternal and paternal chromosomes is distributed into each sperm and each egg.
- Meiosis II
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Describe the 3D structure of DNA.
- two strands of linked nucleotides are bound together and twisted around each other to form a spiral-shapped double helix
- the sugars and phosphates = backbone
- bases = rungs
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Where is DNA found in a cell?
inside the nucleus in the form of chromosomes
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What are the componets of chromosomes?
DNA and protein (histones)
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What holds the sugar and phosphate groups together?
Ester Bonds
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What holds the bases together?
Hydrogen bonds
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What are the three componets of a nucleotide?
a sugar, a phosphate and a base
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Describe the assembly of the nucleotide into the 3D structure of DNA.
- the outside is phosphate groups and sugars alternating
- the middle is A,T,C,G held together by hydrogen bonds attached to a sugar
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Describe the process of DNA replication.
- 1. the helix unwinds and the two strands unzip
- 2. DNA polymerase pairs new nucleotides to each individual DNA strand matich A with T and C with G.
- 3. The end result is 2 molecules of DNA
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What enzyme is involved in DNA replication?
DNA Polymerase
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Is there any difference in the DNA found in different cells of the human body?
No, just different parts of the DNA are being read
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What is PCR?
- Polymerase Chain Reaction
- a laboratory technique used to replicate, and thus ampify, a specific DNA segment
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Describe the steps of PCR.
- 1. Heating- separates DNA strands
- 2. Cooling- Allows DNA polymerase to pair new nucleotides with the original template strand
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What are the "ingredients" required for PCR?
- -DNA
- -Nucleotides A,T,C,G
- -DNA polymerase
- -Primers
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Describe the stpes in running a gel.
- 1. Collect cells and extract DNA from the crime scene evidence.
- 2. PCR amplify multiple STR regions
- 3. Separate STR's using gel electrophoresis
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Why does DNA move through the gel?
because it has a negative charge, and therefore it moves towards the positive end of the gel.
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Coding regions
Sequences of DNA that serve as instructions for making proteins
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Non-Coding regions
DNA sequences that do not hold instructions to make protein
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Are coding or non-coding regions more variable?
Non-coding sequences vary much more between individuals
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Which region is used in making DNA fingerprints?
STR (Short Tandem Repeat) Regions
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How many chromosomes are found in haploid cells?
23
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How many chromosomes are found in diploid cells?
46
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Binary fission
A type of asexual reproduction in which one parental cell divides into two
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Population
a group of organisms of the same species living together in the same geographic area
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Evolution
Chance in allele frequencies in a population over time
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Fitness
The relative ability of an organism to survive and reproduce in a particular environment
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Natural Selection
Differential survival and reproduction of individuals in response to environmental pressure that leads to chance in allele frequencies in a population over time
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Adaptation
The response of a population to environmental pressure, so that advantageous traits become more common in the population over time
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Directional selection
Occurs when a single phenotype predominates in a paticular environment
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Stabilizing selection
occurs when phenotypes at each end of the spectrum are less suited to the environment than organisms in the middle of the phenotypic range
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Diversifying selection
Tupically occurs in a "patchy" environment, in which extremes of the phenotypic range do better than middle range individuals
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