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Introduction to Genetics. Genes= set of instructions for one protein; section of chromosome region of DNA that controls a hereditary characteristic (by making a particular PROTEIN!!). Introduction to Genetics. Trait= characteristic that is expressed and may vary from one individual to another

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Introduction to genetics

Introduction to Genetics

Genes= set of instructions for one protein; section of chromosome

region of DNA that controls a hereditary characteristic (by making a particular PROTEIN!!)


Introduction to genetics1
Introduction to Genetics

  • Trait= characteristic that is expressed and may vary from one individual to another

  • Heredity= passage of genetic information from parents to offspring




Remember these are separated during meiosis
Remember…these are separated during meiosis!! trait.

  • Homologous chromosomes

  • Alleles



Began with mendel
Began with Mendel with a monk and his pea plants


  • The modern science of genetics was founded by an Austrian monk named Gregor Mendel.

  • Mendel was in charge of the monastery garden, where he was able to do the work that changed biology forever.

  • Mendel carried out his work with ordinary garden peas, partly because peas are small and easy to grow. A single pea plant can produce hundreds of offspring.

  • Today we call peas a “model system.”



Gregor mendel the father of genetics
Gregor Mendel… different from those of their parents and then study the results.the “father” of genetics


Mendel s conclusions
Mendel’s Conclusions different from those of their parents and then study the results.


  • Dominant different from those of their parents and then study the results.Trait : the trait will always appear if the gene is present (Capital letter) (Dominant allele= dominant gene)

  • Recessive Trait: the trait that will appear if there are two copies of a gene…..otherwise this trait will be hidden by the dominant trait!! (lower case letter) (Recessive allele=recessive gene….the one that can be covered up)


  • Principle of Segregation different from those of their parents and then study the results.

    • Allele pairs separate or segregate during formation of gametes (MEIOSIS) and recombine during fertilization


Meiosis explains this
Meiosis Explains this different from those of their parents and then study the results.


Principle of independent assortment
Principle of Independent Assortment different from those of their parents and then study the results.

  • Alleles for different traits are separated independently of each other


Mendel s principles
Mendel’s Principles different from those of their parents and then study the results.

  • The inheritance of biological characteristics is determined by individual units called genes.

  • When two or more forms (allele) of the gene for a single trait exist, some alleles may be dominant or recessive

  • In most sexually reproducing organisms, each adult has two copies of each gene– one from each parent. These genes segregate from each other when gametes are formed.

  • Alleles for different traits usually separate independently of each other


Punnett squares
Punnett different from those of their parents and then study the results.Squares

  • chart which shows/predicts all possible gene combinations in a cross of parents (whose genes are known).

  • Actually…..shows possible alleles parents may contribute!!


Dihybrid cross
Dihybrid different from those of their parents and then study the results. Cross


Probability and punnett squares
Probability and Punnett squares different from those of their parents and then study the results.

  • Why are the principles of probability able to be used to predict the outcome of genetic crosses?

  • Think about the “segregation of alleles”!!



Inheritance of traits
Inheritance of Traits trait.

  • During fertilization…the male and female parents each contribute genetic information…to create the zygote

  • Zygote: fertilized egg; cell formed by union of gametes



Karyotype photograph chart of chromosomes in an organism arranged in pairs
Karyotype: normally in the body cell of the organismphotograph/chart of chromosomes in an organism arranged in pairs

  • Can tell gender….and certain diseases


Kleinfelters syndrome
Kleinfelters Syndrome normally in the body cell of the organism


Genetics so far

Genetics so far…… normally in the body cell of the organism

Simple dominant/recessive one trait crosses!

Now……

Incomplete Dominance: a blending of traits; neither allele is completely dominant

Codominance: Each trait is expressed; both alleles are dominant


Incomplete dominance
Incomplete Dominance normally in the body cell of the organism

  • Alleles are neither dominant or recessive

  • The heterozygote phenotype is a blending (lies somewhere between the two)


Codominance
Codominance normally in the body cell of the organism

  • In a heterozygote…..both traits are expressed separately…both are dominant

  • Example…..


Codominance1
Codominance normally in the body cell of the organism

Codominance helps to explain the inheritance of Human Blood Types


Human blood typing
Human Blood Typing normally in the body cell of the organism

  • Blood type is determined by antigen found on red blood cell


Codominance and multiple alleles
Codominance and normally in the body cell of the organismMultiple Alleles!!

  • There are more than two alleles (gene possibilities) (Multiple Alleles)

  • A (I A), B (IB), and O(i)

  • Both A and B are dominant(Codominant)

  • O is recessive


  • If an antigen is introduced to a person that cannot recognize it…they will make antibodies against it…..and attack it!

  • This will cause the blood to clump…clots...

  • So blood types need to be matched

  • If the person can recognize it…they can have it!!


Blood typing process
Blood Typing Process!! recognize it…they will make


Pedigree chart

Pedigree Chart recognize it…they will make

Traces the pattern of inheritance through many generations


  • Female recognize it…they will make

  • Affected Female

  • Male

  • Affected male


Tay sach s
Tay recognize it…they will make Sach’s


Sickle cell anemia
Sickle-cell Anemia recognize it…they will make


Human genetic diseases
Human Genetic Diseases recognize it…they will make

  • PKU: an enzyme needed to metabolize a particular amino acid is absent; if not detected early mental retardation may occur

  • Sickle-cell Anemia: formation of abnormal hemoglobin; makes RBC’s fragile and gives them a sickle shape

  • Tay-Sachs: an enzyme is not synthesized and that allows for an accumulation of a fatty material on nervous tissue; fatal disease

  • Cystic Fibrosis: a non-secretion of digestive enzymes; allows for a abnormal build-up of mucus (recessive) (chromosome 7)

  • Specific disorders

  • Information from Genome Project


  • Albinism recognize it…they will make : inability to produce melanin (recessive)

  • Huntington's Disease: adults lose muscle control, convulsions, nervous degeneration causes death (chromosome 4) (dominant)

  • Polydactyly: dominant disorder that causes extra fingers and toes


Sex determination
Sex determination recognize it…they will make

  • Sex chromosomes: 1 pair of chromosomes…..responsible for determining gender (X or Y)

  • Autosomes: the other 22 pairs of chromosomes ( not sex)


  • Sex chromosomes are represented by recognize it…they will make X and Y

  • Egg cells carry only X chromosomes

  • Sperm cells carry either an X or Y

  • At fertilization: XX=female

    • XY=male


Sex linked inheritance
Sex-Linked Inheritance recognize it…they will make

  • Several genes found on X chromosome but not on Y….X is larger!!

  • Sometimes these genes on the X carry genetic diseases and are called sex-linked genes

  • Usually recessive

  • Females who have one recessive gene and one normal gene are called carriers


Polygenic inheritance
Polygenic Inheritance recognize it…they will make

  • Traits controlled by more than one gene pair (allele)

  • Most human traits are polygenic

    • Skin color, height

      Resulting phenotypes show

      range of differences!!


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