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Heredity & Environment

Heredity & Environment. What created you at the very beginning?. What are genes?. DNA (deoxyribonucleic acid) The basis of heredity Humans = 46 (23 pairs) of chromosomes Chromosome Molecule of DNA Make up chromosomes Genes = Section of chromosomes

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Heredity & Environment

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  1. Heredity & Environment What created you at the very beginning?

  2. What are genes? • DNA (deoxyribonucleic acid) • The basis of heredity • Humans = 46 (23 pairs) of chromosomes • Chromosome • Molecule of DNA • Make up chromosomes • Genes = Section of chromosomes • Allele = Slight normal variation in a gene Genes In cell nucleus  Chromosomes  DNA 

  3. What is the code for making an individual? • Genome = The full set of genes for a specific organism (entire genetic inheritance) • 20,000 genes (99% in other creatures also) • Phenotype • What you look like based on your genes • Appearance, personality, intelligence • Genotype = Hidden in your genes (e.g. Cancer) • Phenotype = Observable characteristics based on genes – E.g. brown eyes

  4. Do you remember? You have how many pairs of chromosomes? Your chromosomes are made up of what type of molecule? What is the genome for a human? What is the difference between your genotype and phenotype?

  5. How does life begin?

  6. What are gamete? Sperm Ovum (egg) Each has 23 chromosomes (one half of 46)

  7. What happens after fertilization? A zygote develops Single cell from two gametes The first stage of development after fertilization of the egg (ovum).

  8. Male or female? 23rdpair of chromosomes Female = XX Male = XY

  9. What creates twins? • Monozygotic (identical) twins • From one zygote • (One egg & sperm) • Share 100% genes • Dizygotic (fraternal) twins • Two sperm penetrating two ova • Share 50% of their genes

  10. Do you remember? After an egg is fertilized, it is called what? The 23rd. Pair of chromosomes in women are: The 23rd. Pair of chromosomes in men are: What is the monozygotic and dizygotic twins?

  11. How can we help fertilization occur? • ART = Assisted Reproduction Technology • IVF = In Vitro Fertilization • Sperm mixed with ova in glass dish • Viable embryos implanted • ICSI (Intracytoplasmic sperm injection) • Intrafallopian sperm injection

  12. From one cell to many:

  13. How do genes affect appearance and behavior? • Genes + Environment = Phenotype (Appearance & behavior) • E.g. Alcoholism • Genes(Varies in intensity) + Environment (Encourages or discourages drinking) = Result • Large breasts and shyness

  14. If something is epigenetic, what is it? • Characteristics that are determined by both genes and environment • E.g. height and nutrition

  15. Additive heredity • Some alleles (gene variations) combine to affect appearance and behavior

  16. Are some genes more powerful than others? Dominant – recessive heredity Dominate genes are more influential than recessive genes. E.g. Brown eyes (Mother-dominate) + Blue eyes (Father-recessive) = Brown eyed child Being a carrier for blue eyes can effect this

  17. What can cause genetic abnormalities? • Most often related to age of mother • E.g.: Extra chromosome • E.g. Down Syndrome = 47 chromosomes

  18. Abnormalities of the 23rd. Pair • Humans have 44 chromosomes + one X + an “X” or ”Y” • Embryos do not develop without one X • Missing chromosome • E.g. XO = Turner’s syndrome (looks female) • Three sex chromosomes • XXY = Klienfelters Syndrome (Looks male) • XYY = “XYY” Syndrome (looks male) • Appear normal until puberty

  19. What is the effect of genetic counseling? Find harmful conditions Affect insurance coverage Jeopardize the marriage

  20. Do you remember? What are some methods of assisted reproduction? How do genes and the environment interact? How do dominate and recessive genes control who you became? What is the most common cause of genetic abnormalities? What are some abnormalities of the sex chromosomes? What are some of the positive and negative effects of genetic counseling?

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