Bell Ringer: Copy the following words to define for homework.

1) Carrier

2) Pedigree

3) Autosome

4) Codominance

5) Incomplete Dominance

6) Multiple Alleles

7) Sex Chromosome

8) Sex-Linked Trait

9) Karyotype

10)Nondisjunction

11)Telomere

12)Deletion

13) Inversion

14)Translocation

15)Down Syndrome

16)Turner’s Syndrome

17)Klinefelter’s Syndrome

Benchmark Test Info

• Point Breakdown• 52 pts Participation• 48 pts (2pts each) for the

24 questions we’ve already covered.

• TALKING/LOOKING AROUND will result in the loss of your 52 participation points.

Bell-Ringer• Grab a packet of

guided notes from the back table.

Complex Inheritanceand Human Heredity 11

The Big Idea

Human inheritance does not always follow

Mendel’s laws.

Main Idea #1The inheritance of a trait over several

generations can be shown in a pedigree.

Recessive Genetic Disorders• Remember - recessive traits can be masked

by a dominant trait.

• Therefore, a person who is heterozygous for a characteristic may be considered a carrier for that trait since it will not be expressed.

• Even though a carrier is not affected by the trait, they can pass the trait on to future generations.

• In order for the recessive trait to show in the individual, the person must be homozygous recessive.

Common Recessive Disorders• Cystic Fibrosis

• Affects the mucus-producing glands, digestive enzymes, and sweat glands

• Chloride ions are not absorbed into the cells of a person with cystic fibrosis but are excreted in the sweat

• Without sufficient chloride ions in the cells, a thick mucus is secreted

• The mucus clogs ducts in the pancreas, causes problems with digestion, and blocks some of the tiny passages in the respiratory system.

Common Recessive Disorders• Albinism

• Caused by altered genes, resulting in the absence of melanin (color pigment) in the hair and eyes

• Common characteristics include: white hair, very pale skin, and pink pupils

• Tay-Sachs Disease• Caused by the absence of an enzyme responsible for

breaking down fatty acids

• The fats begin accumulating in the brain, destroying brain cells and mental deterioration.

Dominant Genetic Disorders• Some genetic disorders are controlled by a dominant

allele.

• People who have only one copy of this allele will display the trait. Only those who are homozygous recessive will not have the disorder.

• Huntington’s Disease

• Disease that gradually destroys the nervous system. Symptoms usually begin between the ages of 30 and 50.

• Achondroplasia

• Genetic condition that causes small body size and limbs that are comparatively short. This is the most common form of dwarfism.

Pedigrees• A pedigree is a diagram that traces the inheritance

of a particular trait through several generations.

• Males are represented by squares, and females by circles.

• One who is affected by the trait will have a symbol that is colored in, while those that are unaffected by the trait will have an unfilled symbol.

Pedigree

Let’s Practice!!!Make this correction:

• Second question for #3 should read, What are the sexes of the

children?

Main Idea #3Chromosomes can be studied using

karyotypes.

Karyotypes

• A karyotype is a picture of a person’s chromosomes.

• Chromosomes are taken from the stage of metaphase and stained.

• They are then placed in order of decreasing size. The last pair is the sex chromosome pair.

• Disorders caused by an incorrect number of chromosomes or malformed chromosomes are the easiest to identify using a karyotype.

Normal Karyotypes

Telomeres

• Telomere caps consist of DNA associated with proteins.

Nondisjunction

• Homologous chromosomes separate during the final steps of meiosis to ensure that each developing sperm or egg receives one copy of each chromosome.

• Nondisjunction is the failure of a pair of homologous chromosomes to separate properly.

• Resulting sex cells will either have an extra chromosome (trisomy) or a missing chromosome (monosomy).

Down Syndrome• One of the most common

disorders due to nondisjunction is Down syndrome, also known as trisomy 21.

• Down syndrome occurs when the person has a third copy of the 21st chromosome.

• Common features include: short stature, heart defects, distinctive facial features, and mental disability.

Disorders Due to Nondisjunction of Sex Chromosomes

Klinefelter Syndrome

(XXY)

Jacob’s Syndrome

(XYY)

Turner’s Syndrome

(XO)

Trisomy X Syndrome

(XXX)

Types of Mutations• Mutations can involve an entire chromosome or a

single DNA nucleotide, and they may take place in any cell.

• Germ-cell mutations occur in an organism’s gametes (germ cells).

• These do not affect that organism, but may be passed on to their offspring the germ cell becomes fertilized.

• Somatic mutations occur in an organism’s body cells and can affect the organism.

• These mutations cannot be passed on to offspring.

• Some examples include skin cancer and leukemia.

• Lethal mutations cause death, usually before birth.

Chromosome Mutations• Deletion (1)- results in

the loss of a piece of chromosome due to the breakage of that chromosome; genetic information will be lost

• Duplication (2)- results in the copying of a segment of the chromosome

• Inversion (3)- a segment of a chromosome breaks off and reattaches itself to the chromosome in a reversed order

Chromosome Mutations• Insertion (1) - a

segment of a chromosome breaks off and reattaches itself to another homologous chromosome

• Translocation (2) - segments of chromosomes break off and exchange places on different chromosomes

Chromosome Mutations• Nondisjunction is also a type of

chromosome mutation. It affects the total number of chromosomes instead of pieces of individual chromosomes.

Bell-RingerCopy your homework for the week!

1/13 – 1/17 Homework:Monday: Chapter 11 Assessment pg. 319-321

1-30 Omit #s 11, 16, 18, 19, 20, 27, 28

Tuesday: STUDY FOR TEST

Wednesday: Ch. 12 Vocab

BRING YOUR BOOK THURSDAY

Thursday: Finish Ch. 12 Guided Reading

Friday: NONE

Genetic Disorder Foldable

1. Achondroplasia2. Albinism3. Cystic Fibrosis4. Down Syndrome5. Huntington’s

Disease6. Klinefelter

Syndrome

7. Sex-Linked8. Tay-Sachs9. Turner’s

SyndromeTell if the listed disorders

are dominant or recessive and give a brief

description of each.For Sex-Linked describe

the two that we discussed in class.