Unit 4 Genetics : Unit 4 Genetics Ch. 14 The Human Genome
Human Chromosomes : Human Chromosomes To analyze chromosomes, biologists photograph cells in mitosis
They then cut out the chromosomes from the photograph, & group them together in pairs
Human Chromosomes : Human Chromosomes Karyotype - a picture of chromosomes arranged in pairs
Human Chromosomes : Human Chromosomes Sex chromosomes - 2 of the 46 chromosomes, that determine an individual’s sex
Females: XX
Males: XY
Autosomes - remaining 44 chromosomes
Human Traits : Human Traits Pedigree - chart that shows the relationships within a family
Human Traits : Human 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
Human Genes : Human 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
Human Genes : Human Genes Many genetic disorders are caused by autosomal recessive alleles
Human Genes : Human 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)
From Gene to Molecule : From 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
From Gene to Molecule : From 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 : Cystic Fibrosis
From Gene to Molecule : From 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)
Human Genes & Chromosomes : Human 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
Sex-Linked Genes : Sex-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 : Sex-Linked Genes Ex. of sex-linked disorders: colorblindness, hemophilia, muscular dystrophy
Chromosomal Disorders : Chromosomal 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
Chromosomal Disorders : Chromosomal Disorders Down Syndrome results when there is an error on chromosome 21
Human DNA Analysis : Human DNA Analysis DNA Fingerprinting - (Gel Electrophoresis), analyzes sections of DNA that vary from 1 individual to another
DNA Fingerprinting : DNA Fingerprinting
The Human Genome Project : The Human Genome Project 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 Therapy : Gene 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
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?