chapter 6 modern genetics 6.1 human inheritance 6.2 human genetic disorders 6.3 advances in genetics...

Chapter 6 Modern Genetics

6.1 Human Inheritance

6.2 Human Genetic Disorders

6.3 Advances in Genetics

Table of ContentsChapter Preview

1.1 Thinking Like a Scientist

1.2 The Study of Life

1.3 Scientific Inquiry

1.4 Safety in the Laboratory

Chapter Preview

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.



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.



3. The genetic material of living organisms is

a. cytoplasm.

b. mitochondria.

c. chromosomes.

d. DNA.



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.


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.

How are traits inherited in people?


High-Use Academic Words

Word Definition Example Sentence

normal adj. Usual, typical,expected

Its normal to feel nervous about going to a new school.




structuren. The way in which parts of something are connected

You have learned the basicstructure of plant and animal cells.




affectv. To influence; toproduce a change in

Scientists are looking for ways to treat diseases that affect people.




techniquen. A special way ofdoing something, amethod, a procedure

There are special techniques for balancing on a skateboard.


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?

Chapter 6 Modern GeneticsPatterns 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 AllelesMultiple 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.

Chapter 6 Modern GeneticsThe 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 XXMales 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


Colorblindness

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 diseasecaused 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-linkedBlood cots very slowly or

not at allPerson 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


• This pedigree shows the inheritance of hemophilia in a family.

• 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


A Hemophilia Pedigree

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


Managing Genetic DisordersKey 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

Chapter 6 Modern GeneticsManaging Genetic Disorders

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

Karyotyping

Punnett square

Pedigree


Managing Genetic DisordersDealing 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?


Selective Breeding

• 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


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

• 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- genes from one organism are put into the DNA of another

• Genetic engineering can produce and improve medicines and foods.


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


Human genome projectProject 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

chapter 6 modern genetics 6.1 human inheritance 6.2 human genetic disorders 6.3 advances in genetics...

Documents

modern genetics high

laboratory chapter preview

varying copies

human genetic disorders

human inheritance

animal cells

special way

basic structure of plant