Table of Contents Chapter Preview 6.1 Human Inheritance 6.2 Human Genetic Disorders 6.3 Advances in Genetics Chapter Preview 1.1 Thinking Like a Scientist 1.2 The Study of Life 1.3 Scientific Inquiry 1.4 Safety in the Laboratory 6.1 Human Inheritance 6.2 Human Genetic Disorders 6.3 Advances in Genetics

Chapter Preview Questions 1. From each parent, offspring inherit a. half their phenotypes. b. half their traits. c. half their genes. d. half their chromosomes.

Chapter Preview Questions 1. From each parent, offspring inherit a. half their phenotypes. b. half their traits. c. half their genes. d. half their chromosomes.

Chapter Preview Questions 2. Plant and animal cells typically have a. three copies of every gene. b. two copies of every gene. c. varying copies of every gene. d. one copy of every gene.

Chapter Preview Questions 2. Plant and animal cells typically have a. three copies of every gene. b. two copies of every gene. c. varying copies of every gene. d. one copy of every gene.

Chapter Preview Questions 3. The genetic material of living organisms is a. cytoplasm. b. mitochondria. c. chromosomes. d. DNA.

Chapter Preview Questions 3. The genetic material of living organisms is a. cytoplasm. b. mitochondria. c. chromosomes. d. DNA.

Chapter Preview Questions 4. The chromosomes of each cell in an organism are where a. DNA is located. b. sexual reproduction occurs. c. gender identity is determined. d. photosynthesis takes place.

Chapter Preview Questions 4. The chromosomes of each cell in an organism are where a. DNA is located. b. sexual reproduction occurs. c. gender identity is determined. d. photosynthesis takes place.

How are traits inherited in people? Suppose you have a friend who doesn’t have freckles. Both of her biological parents have freckles. The allele for freckles is dominant. What can you infer about the genotype of your friend’s parents? Explain your answer.

High-Use Academic Words Definition Example Sentence adj. Usual, typical, expected Its normal to feel nervous about going to a new school. normal

High-Use Academic Words Definition Example Sentence n. The way in which parts of something are connected You have learned the basic structure of plant and animal cells. structure

High-Use Academic Words Definition Example Sentence v. To influence; to produce a change in Scientists are looking for ways to treat diseases that affect people. affect

High-Use Academic Words Definition Example Sentence n. A special way of doing something, a method, a procedure There are special techniques for balancing on a skateboard. technique

Apply It! Choose the word that best completes each sentence. 1. People’s diets can their health. affect 2. Doctors have developed a new for doing heart surgery. technique 3. A(n) body temperature in a human is about 37°C. normal

End of Chapter Preview

Section 1: Human Inheritance What are some patterns of inheritance in humans? What are the functions of the sex chromosomes? What is the relationship between genes and the environment?

Patterns of Human Inheritance A single gene can have more than two alleles There is not always a one-to-one correspondence between trait and gene Key concept: “Some human traits are controlled by single genes with two alleles, and other by single genes with multiple alleles. Still other traits are controlled by many genes that act together.” What we discussed in chapter 5: single gene with 2 alleles

Single Genes with Multiple Alleles Multiple alleles- 3 or more forms of a gene that code for a single trait. People carry only 2 alleles for each trait Each chromosome carries one allele for each gene Blood type is determined by a single gene with three alleles. This chart shows which combinations of alleles result in each blood type.

Traits Controlled by Many Genes Some traits show a large number of phenotypes because the traits are controlled by multiple alleles (ex. Height) Skin, eyes, hair color are also controlled by multiple alleles

The Sex Chromosomes The sex chromosomes carry genes that determine whether a person is male or female. They also carry genes that determine other traits.

Sex chromosomes are one of the 23 pairs of chromosomes in a human body The Sex Chromosomes Key concept: “The sex chromosomes carry genes that determine whether a person is male or female. They also carry genes that determine other traits.” Sex chromosomes are one of the 23 pairs of chromosomes in a human body Only chromosomes that sometimes don’t match Females have XX Males have XY

Sex Linked Genes Sex-linked Genes- genes on the X or Y chromosomes, these are passed from parent to offspring on the sex chromosome Many of the genes on the X chromosomes are not on the Y chromosomes Because males have only one X they are more likely to have a sex-linked gene than females

Colorblindness Punnett Square Red-green colorblindness is a sex-linked trait. A girl who receives only one recessive allele (written Xc) for red-green colorblindness will not have the trait. However, a boy who receives one recessive allele will be colorblind. Carrier- person who has one recessive allele for a trait and one dominant

What sex is the person that is a carrier for colorblindness?

The Effect of Environment Key concept: “Many of an organism’s characteristics are determined by an interaction between genes and the environment.” A diet lacking in protein, minerals, vitamins, … can affect growth

End of Section: Human Inheritance

Section 2: Human Genetic Disorders What are two major causes of genetic disorders in humans? How do geneticists trace the inheritance of traits? How are genetic disorder diagnosed and treated?

Cause of Genetic Disorders Genetic disorder- an abnormal condition that a person inherits through genes or chromosomes Key concept: “Some genetic disorders are caused by changes in the DNA of genes. Other disorders are caused by changes in the overall structure or number of chromosomes.”

A Pedigree A pedigree is a chart or “family tree” that tracks which members of a family have a particular trait.

Genetic Disorders Cystic Fibrosis Sickle-cell disease caused by a recessive allele as a result of a mutation body produces abnormally thick mucus in the lungs and intestines makes it hard to breathe codominant with normal cells person with two sickle-cell alleles has the disease person with one sickle-cell allele has both normal and abnormal hemoglobin unusual shaped blood cells that clogs the blood vessels

Genetic Disorders Hemophilia Down Syndrome Caused by a recessive allele on the X chromosome Sex-linked Blood cots very slowly or not at all Person doesn’t produce one of the proteins needed for clotting Extra copy of chromosome 21 Most often happens when a chromosome fails to separate during meiosis

A Hemophilia Pedigree Pedigree- a chart that tracks members of a family with a particular trait Key Concept: “One important tool that geneticists use to trace the inheritance of traits in humans is a pedigree.” Pedigrees can be about normal traits like widow’s peak or genetic disorders This pedigree shows the inheritance of hemophilia in a family.

A Hemophilia Pedigree The pedigree shows the inheritance of hemophilia, a sex-linked disorder in a family.

Managing Genetic Disorders Key Concept: “Today, doctors use tools such as karyotypes to help diagnose genetic disorders. People with genetic disorders are helped through medical care, education, job training, and other methods.” Doctor’s use Punnett squares and pedigrees to help predict whether a child might have a genetic disorder or not Karyotype- a picture of all the chromosomes in a cell showing if a person has the correct number of chromosomes or not

Managing Genetic Disorders Karyotyping Genetic counseling Families that have a history of a genetic disorder Help people understand the chances of having a child with a specific disorder Use Punnett squares, pedigrees, karyotypes to help Punnett square Pedigree

Managing Genetic Disorders Dealing with Genetic Disorders Deal with serious challenges Modify environment Medicine, diet, and vitamins Education People can still live active and productive lives

End of Section: Human Genetic Disorders

Section 3: Advances in Genetics What are three ways of producing organisms with desired traits? What are two applications of DNA technology in human genetics?

Key concept: “Selective breeding, cloning, and genetic engineering are three methods for developing organisms with desirable trait.” Selective breeding- the process of breeding organisms with desired traits Inbreeding- crossing two individuals that have similar characteristics Inbreeding increases the probability of having genetic disorders Hybridization- breeders cross two genetically different individuals trying to get the best of both organisms Selective Breeding

Cloning Clone- an organism that has the exact same genes as the organism from which it was produced You can clone some plants easily because all you do is cut a piece off and plant it- new plant is genetically identical to the original plant Animals are more difficult to clone, they take the nucleus out of a body cell and use it to produce a new animal

Genetic Engineering Genetic engineering- genes from one organism are put into the DNA of another Genetic engineering can produce and improve medicines and foods. Genes have been inserted into animals (example- creating blood clotting protein to help people with hemophilia Genes have been inserted into plants (example- creating crops that are resistant to pesticides Gene therapy- inserting copies of a gene into a human’s cells Concerns about the long-term effects of genetic engineering (crops harm environment or health problems in people )

Genetic Engineering Scientists use genetic engineering to create bacterial cells that produce important human proteins such as insulin.

Learning About Human Genetics Key concept: “Applications of DNA technology include studying the human genome in detail and identifying people.” Genome- all the DNA in one cell of an organism DNA finger printing is used to show if people are related using Except for identical twins every person has different DNA fingerprints Scientists use mitochondrial DNA, because it is almost identical to the mother, to determine the person’s identity

Scientists now know the DNA sequence of almost every human gene Human genome project Project goals were to… identify all the approximately 30,000-35,000 genes in human DNA determine the sequences of the 3 billion chemical base pairs that make up human DNA store this information in databases improve tools for data analysis Scientists now know the DNA sequence of almost every human gene

End of Section: Advances in Genetics