Unit 4 GeneticsUnit 4 Genetics

Ch. 14 The Human GenomeCh. 14 The Human Genome

Human ChromosomesHuman Chromosomes

To analyze chromosomes, biologists photograph cells in mitosis

They then cut out the chromosomes from the photograph, & group them together in pairs

To analyze chromosomes, biologists photograph cells in mitosis

They then cut out the chromosomes from the photograph, & group them together in pairs

Human ChromosomesHuman Chromosomes

Karyotype - a picture of chromosomes arranged in pairs

Karyotype - a picture of chromosomes arranged in pairs

Human ChromosomesHuman Chromosomes

Sex chromosomes - 2 of the 46 chromosomes, that determine an individual’s sex– Females: XX– Males: XY

Autosomes - remaining 44 chromosomes

Sex chromosomes - 2 of the 46 chromosomes, that determine an individual’s sex– Females: XX– Males: XY

Autosomes - remaining 44 chromosomes

Human TraitsHuman Traits

Pedigree - chart that shows the relationships within a family

Pedigree - chart that shows the relationships within a family

Human TraitsHuman Traits

Remember that the phenotype of an organism is determined by its genotype

Also, that environmental effects on gene expression are not inherited, genes are

Remember that the phenotype of an organism is determined by its genotype

Also, that environmental effects on gene expression are not inherited, genes are

Human GenesHuman Genes

The human genome, our complete set of genetic information, includes 10’s of 1000’s of genes

The DNA sequences on these genes carry information for specifying many characteristics

The human genome, our complete set of genetic information, includes 10’s of 1000’s of genes

The DNA sequences on these genes carry information for specifying many characteristics

Human GenesHuman Genes

Many genetic disorders are caused by autosomal recessive alleles

Many genetic disorders are caused by autosomal recessive alleles

Human GenesHuman Genes

However, some genetic disorders may be caused by a dominant allele

Ex.) Dwarfism, Huntington’s Disease (loss of muscle control, & mental function until death occurs)

However, some genetic disorders may be caused by a dominant allele

Ex.) Dwarfism, Huntington’s Disease (loss of muscle control, & mental function until death occurs)

From Gene to MoleculeFrom Gene to Molecule

In cystic fibrosis, & sickle cell disease, a small change in the DNA of a single gene affects the structure of a protein, causing a serious genetic disorder

In cystic fibrosis, & sickle cell disease, a small change in the DNA of a single gene affects the structure of a protein, causing a serious genetic disorder

From Gene to MoleculeFrom Gene to Molecule

Cystic fibrosis is caused by the deletion of 3 bases in the DNA of a single gene– As a result, the body does not produce a protein

needed to transport chloride ions– CF causes serious digestive & respiratory

problems

Cystic fibrosis is caused by the deletion of 3 bases in the DNA of a single gene– As a result, the body does not produce a protein

needed to transport chloride ions– CF causes serious digestive & respiratory

problems

Cystic FibrosisCystic Fibrosis

From Gene to MoleculeFrom Gene to Molecule

Sickle cell disease is common in African Americans– It is characterized by the bent & twisted shape

of the red blood cells– The cells get stuck in the capillaries, damaging

cells, tissues, & organs– It causes physical weakness, & damage

to the brain, heart, & spleen (may be fatal)

Sickle cell disease is common in African Americans– It is characterized by the bent & twisted shape

of the red blood cells– The cells get stuck in the capillaries, damaging

cells, tissues, & organs– It causes physical weakness, & damage

to the brain, heart, & spleen (may be fatal)

Human Genes & ChromosomesHuman Genes & Chromosomes

Genes located close together on the same chromosome are linked, so they tend to be inherited together

Linked genes may be separated, however, during crossing-over

Genes located close together on the same chromosome are linked, so they tend to be inherited together

Linked genes may be separated, however, during crossing-over

Sex-Linked GenesSex-Linked Genes

Sex-linked genes - genes located on the sex chromosomes

Males have 1 X chromosome, therefore, all X-linked alleles are expressed in males, even if they

are recessive

Sex-linked genes - genes located on the sex chromosomes

Males have 1 X chromosome, therefore, all X-linked alleles are expressed in males, even if they

are recessive

Sex-Linked GenesSex-Linked Genes

Ex. of sex-linked disorders: colorblindness, hemophilia, muscular dystrophy

Ex. of sex-linked disorders: colorblindness, hemophilia, muscular dystrophy

Chromosomal DisordersChromosomal Disorders

Nondisjunction - when homologous chromosomes fail to separate during meiosis

If it occurs, abnormal #’s of chromosomes could find their way into gametes, & a disorder of chromosome #’s may result

Nondisjunction - when homologous chromosomes fail to separate during meiosis

If it occurs, abnormal #’s of chromosomes could find their way into gametes, & a disorder of chromosome #’s may result

Chromosomal DisordersChromosomal Disorders

Down Syndrome results when there is an error on chromosome 21

Down Syndrome results when there is an error on chromosome 21

Human DNA AnalysisHuman DNA Analysis

DNA Fingerprinting - (Gel Electrophoresis), analyzes sections of DNA that vary from one individual to another

DNA Fingerprinting - (Gel Electrophoresis), analyzes sections of DNA that vary from one individual to another

DNA FingerprintingDNA Fingerprinting

The Human Genome ProjectThe Human Genome Project

Genome- the entire genetic makeup of an organism

The Human Genome Project is an ongoing effort to analyze the human DNA sequence

Biotechnology companies are rushing to find genetic info. that may be used

in developing new drugs &

treatments for diseases

Genome- the entire genetic makeup of an organism

The Human Genome Project is an ongoing effort to analyze the human DNA sequence

Biotechnology companies are rushing to find genetic info. that may be used

in developing new drugs &

treatments for diseases

Gene TherapyGene Therapy

In gene therapy, an absent or faulty gene is replaced by a normal, working gene

Viruses are often used because they can enter cells so easily

In gene therapy, an absent or faulty gene is replaced by a normal, working gene

Viruses are often used because they can enter cells so easily

Ethical Issues in Human Genetics

Ethical Issues in Human Genetics

The goal of biology is to gain a better understanding of the nature of life

As our knowledge increases, so does our ability to change the genetics of living things, including humans

What will happen to the human species if we design our bodies?

The goal of biology is to gain a better understanding of the nature of life

As our knowledge increases, so does our ability to change the genetics of living things, including humans

What will happen to the human species if we design our bodies?