The Human Genome

The Human Genome

Extending Mendelian Genetics Chapter 7 Mr. Scott Human Heredity Human body 46 chromosomes Haploid sperm cell with 23

chromosomes Haploid egg cell with 23 chromosomes They form a diploid zygote or fertilized egg cell with 46 chromosomes Human Heredity

Sex chromosomes 2 of the 46 chromosomes Determine the sex of that person Females have X and X or XX chromosomes Males have X and Y or XY chromosomes

Human Heredity Autosomes (Autosomal Chromosomes) The other 44 chromosomes found in all body cells These are the chromosomes separate from the

sex cells Typically numbered on a karyotype Human Heredity Human traits Pedigree chart Shows the relationship

within a family Shows how traits may be passed through generations Human Heredity Human genes Blood group genes

Rh blood groups Positive and negative Rh+ is dominant ABO blood groups IA, I B, and i IA and I B are codominant

Human Heredity Recessive alleles Genetic disorders usually are not discovered until seen in the environment Dominant alleles

Anyone carrying an allele will have the disorder Epistasis one of the polygenic genes turns all the others off Human Heredity From

gene to molecule Cystic fibrosis Common in people from northern Europe Serious digestive and breathing problems Caused by the deletion of just one amino acid

Human Heredity Sickle cell disease Blood cells doughnut or comma shaped Heterozygous people dont contract malaria Humans with all sickle celled blood can die

Why do so many African Americans have sickle celled blood? Human Chromosomes Human genes and chromosomes One cell has 6 billion base pairs or A,C,T,& G

46 Chromosomes are found in every diploid human cell Human Chromosomes Only 2% of all DNA is used for genes or transcribed into RNA Average genes are

3,000 base pairs Largest gene is 2 million base pairs Human Chromosomes Chromosomes 21 and 22 are the smallest 22 has 545 genes (43

million base pairs) 21 has 225 genes (21 million base pairs) Lou Gehrigs Disease or Amyotrophic Lateral Sclerosis(ALS) Human Chromosomes Human Chromosomes

Sex-linked genes genes located on the sex chromosomes Colorblindness Red-green colorblindness 1 in 10 males 1 in 100 females

Why do more males have colorblindness? Human Chromosomes Hemophilia Blood does not clot properly Is determined by two genes on the

X-chromosome 1 in 10,000 males Ryan White Human Chromosomes Duchenne Muscular Dystrophy Progressive weakening and loss of skeletal muscle

1 in 3,000 males Caused by a defective gene that codes for a protein in muscles Human Chromosomes X-chromosome inactivation Barr body dense area in a nucleus

where the inactivated X chromosome is located Each cell controls which X chromosome is turned off Calico cat Human Chromosomes

Chromosomal Disorders Nondisjunction error in which homologous chromosomes fail to separate Human Chromosomes

Down syndrome Caused by trisomy or three copies of chromosome 21(Trisomy 21) 1 in 800 babies This is a nondisjunction condition Human Chromosomes Sex

chromosome disorders Turners syndrome Females (45,X) Sterile No sex organs Klinefelters

syndrome Males (47, XXY) Sterile Linkage and Gene Maps Gene linkage Chromosomes assort independently,

not individual genes Linkage and Gene Maps Gene linkage was explained through fruit flies. Morgan found that linked traits are on the same chromosome. Chromosomes, not genes, assort independently during

meiosis. Linkage and Gene Maps Gene maps Shows the exact location of each known gene on one

chromosome Linkage and Gene Maps The frequency of crossing over is related to the distance between two genes Gene A-B 8%, Gene B-C 10%, Gene A-C 2% How many units apart?

What is the order of the genes? Linkage and Gene Maps Linkage maps estimate distances between genes. The closer together two genes are, the more

likely they will be inherited together. Cross-over frequencies are related to distances between genes. Human Molecular Genetics Human DNA analysis Search the human genome using sequences of DNA

bases Human Molecular Genetics DNA fingerprinting No two humans are exactly alike Analyze and compare low function DNA

segments Human Molecular Genetics The Human Genome Project An ongoing effort to analyze the human sequence Finished in 2000

Human Molecular Genetics A breakthrough for everyone Public access to Human genome project Human Molecular Genetics Gene

therapy Changing the gene that causes a genetic disorder Use viruses to infect cells with good gene 1999 - First person cured of genetic disorder

Human Heredity Human chromosomes Karyotype a picture of chromosomes arranged in pairs Human Heredity

Human Molecular Genetics Ethical issues in human genetics Should we use genetics to make people better?

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