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 6 Modern 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 6 Modern 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 6 Modern Genetics
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 6 Modern Genetics
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 6 Modern Genetics
Chapter Preview Questions
3. The genetic material of living organisms is
a. cytoplasm.
b. mitochondria.
c. chromosomes.
d. DNA.
Chapter 6 Modern Genetics
Chapter Preview Questions
3. The genetic material of living organisms is
a. cytoplasm.
b. mitochondria.
c. chromosomes.
d. DNA.
Chapter 6 Modern Genetics
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 6 Modern Genetics
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 6 Modern Genetics
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?
Chapter 6 Modern Genetics
High-Use Academic Words
Word Definition Example Sentence
normal adj. Usual, typical,expected
Its normal to feel nervous about going to a new school.
Chapter 6 Modern Genetics
High-Use Academic Words
Word Definition Example Sentence
structuren. The way in which parts of something are connected
You have learned the basicstructure of plant and animal cells.
Chapter 6 Modern Genetics
High-Use Academic Words
Word Definition Example Sentence
affectv. To influence; toproduce a change in
Scientists are looking for ways to treat diseases that affect people.
Chapter 6 Modern Genetics
High-Use Academic Words
Word Definition Example Sentence
techniquen. A special way ofdoing something, amethod, a procedure
There are special techniques for balancing on a skateboard.
Chapter 6 Modern Genetics
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
Chapter 6 Modern Genetics
End of Chapter Preview
Chapter 6 Modern Genetics
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
Chapter 6 Modern Genetics
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.
Chapter 6 Modern Genetics
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
Chapter 6 Modern Genetics
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
Chapter 6 Modern Genetics
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
Chapter 6 Modern Genetics
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
Chapter 6 Modern Genetics
Colorblindness
What sex is the person that is a carrier for colorblindness?
Chapter 6 Modern Genetics
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
Chapter 6 Modern Genetics
End of Section: Human Inheritance
Chapter 6 Modern Genetics
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?
Chapter 6 Modern Genetics
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.”
Chapter 6 Modern Genetics
A Pedigree
A pedigree is a chart or “family tree” that tracks which members of a family have a particular trait.
Chapter 6 Modern Genetics
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
Chapter 6 Modern Genetics
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
Chapter 6 Modern Genetics
• 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
Chapter 6 Modern Genetics
A Hemophilia Pedigree
The pedigree shows the inheritance of hemophilia, a sex-linked disorder in a family.
Chapter 6 Modern Genetics
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
Chapter 6 Modern Genetics
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
Chapter 6 Modern Genetics
End of Section: Human Genetic
Disorders
Chapter 6 Modern Genetics
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?
Chapter 6 Modern 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
Chapter 6 Modern Genetics
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
Chapter 6 Modern Genetics
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.
Chapter 6 Modern Genetics
Genetic Engineering
Scientists use genetic engineering to create bacterial cells that produce important human proteins such as insulin.
Chapter 6 Modern Genetics
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
Chapter 6 Modern Genetics
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
Chapter 6 Modern Genetics
End of Section: Advances in
Genetics
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