Inheritance Patterns and Human Genetics

Learning Intention Fill In

• Understand how the patterns of ___________ ____________can used to _________ and ___________ genetic disorders.

Learning Intention

• Understand how the patterns of genetic inheritance can used to identify and predict genetic disorders.

Linkage Groups

• The genes located on one chromosome

Small Group Discussion: Why are linkage groups significant? (think about the learning intention…)

X – Linked GenesY – Linked Genes

What do these 2 terms have in common?

How are they different?

Gender Determination

In Humans: • XX – Female• XY – Male

What is the % chance that a couples first child will be a boy? Explain.

Mapping Chromosomes & Genetic Changes

Chromosome Mapping

• A diagram that shows the linear sequence of genes on a chromosome

• How are Chromosome maps constructed?– The greater the distance between two genes, the

greater likelihood that they will be separated during crossing over.

– Distances between genes are represented in map units.

– Ex: 2 map units indicates that the genes cross over 2% of the time.

Mutations

• Any change in the DNA sequence

What causes mutations???

• Errors in replication, transcription, cell division, or by external agents

– External agents that cause mutations are called mutagens.

– Cancer causing mutagens are called carcinogens

Where do mutations occur?

• Reproductive Cells: gametes– Altered reproductive cells will become a part of

the genetic makeup of the offspring• Body Cells: Somatic cells– These mutations are NOT passed down to

offspring– May cause damage to the cell

2 Classes of Mutations

• Gene Mutation• Chromosomal Mutation

Gene Mutation: Change in the DNA sequence

• Point Mutations: the change in one base pair of DNA– One nucleotide was switched

Why is this a big deal????– Changing the DNA sequence can change the

amino acid that it codes for which can changes the proteins ability to function properly!!!!

• Frameshift mutation: (Insertion or Deletion) when a single base is lost or added to the sequence of DNA– This shifts the reading frame for the resulting

mRNA codon sequence and thus almost every amino acid in the sequence would be changed.

Chromosomal AlterationsDeletion Inversion

Translocation

Non-disjunction

Detecting Human Genetic Disorders

• Genetic Screening• Amniocentesis• Chorionic Villi Sampling

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Password: Last 2 ID # then b-day mmddyy

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Please let me know if you need help!Learning.Genetics Activity