Biology I Chapter 12

1. Biology IChapter 12 Inheritance Patterns and Human Genetics

2. Do Now How could an apple farmer increase the number of genotypes and phenotypes present in his next apple crop? • A. It would be impossible for a farmer to increase the genetic variation of plants. • B. Make genetic clones of plants using asexual reproduction. • C. Cross plants that have very different characteristics. • D. Cross plants that have the same characteristics. • Answer: C

3. Do Now Which of the following is a source of genetic variation in sexually-reproducing organisms? A. meiosis B. mitosis C. translation D. all of these Answer: A

4. Do Now • Organisms are able to reproduce either sexually or asexually. Which of the following statements is true of these reproductive processes? • A. The sorting of genes during asexual reproduction results in a large amount of genetic variation. • B. During every cell division in sexual reproduction, the number of chromosomes is reduced by half. • C. The sorting of genes during sexual reproduction results in a large amount of genetic variation. • D. During every cell division in asexual reproduction, the number of chromosomes is reduced by half. • Answer: C

5. Do Now (Do in student notes section) What is the difference between dominant and recessive? What is the relationship between gene expression and natural selection?

6. Sex Chromosomes Autosomes-not directly involved in determining the sex of an individual. Sex Chromosomes-contain genes that determine the sex (gender) of an individual. XX=Female XY=Male

7. Sex-Linked Genes Sex-linked Trait-a trait that is coded for by allele on a sex chromosome. A trait that is determined by a gene found only on the X chromosome Occurs most commonly in males. Ex. Colorblindness

9. A cat's coloring is mostly determined by genes on their X chromosomes, which contain alleles for colors, such as black, orange, gray, and cream. The allele for white fur is located on a different gene. • Calico cats, by definition, must display three different colors in their fur - white plus two of the other colors. This is easily possible in female cats, because females normally possess two X chromosomes. However, this occurs rarely in male cats, because males typically possess only one X chromosome plus one Y chromosome. • What must be the genetic make-up of a male calico cat, and what type of chromosome disorder does this most resemble? A. XXY, Klinefelter's syndrome B. XO, Turner's syndrome C. XYY, Cri-du-chat syndrome D. XX, Down's syndrome

10. Do Now • Unique heritable characteristics can result from • I. mutations of genes in an organism's sex cells. • II. mutations of genes in an organism's body cells. • III. recombination of existing genes during sexual reproduction. • IV. replication of existing genes during asexual reproduction. • A. I, II, III, and IV • B. II and IV only • C. I, II, and III only • D. I and III only Answer: D

11. Linked Genes Linked Genes-pairs of genes that tend to be inherited together.

12. Do Now Most heritable differences are due to • A. the insertion of incorrect sequences of DNA by faulty polymerases. • B. gene shuffling that occurs during the production of gametes. • C. the inability to form proper DNA sequences due to poor nutrition. • D. point mutations that occur during mitosis. • Answer: B

13. Do Now • A mutation occurs in a brain cell. This mutation will be passed on to • A. offspring. • B. other body cells. • C. cells produced when the mutant cell divides. • D. neighboring brain cells. Answer: C

16. Chromosome Map Chromosome Map-a diagram that shows the linear order of genes on a chromosome.

17. Do Now • What are chromosomes that do not code for gender called? • Autosomes • What are the female sex chromosomes? • XX • What are the male sex chromosomes? • XY

18. Mutations A change in a gene due to damage or incorrect copying Spontaneous changes in genetic material The effects of a mutation can be: Helpful (Adaptation) Harmful Neutral Mutation Mutation Repair

19. Mutations Germ-cell mutation-occur in an organism’s gametes; can be passed on to offspring Somatic-cell mutation-take place in an organism’s body cells and can therefore affect the organism; cannot be passed on to offspring Lethal mutation-causes death, often before birth

21. Do Now • Body cell mutations cannot be passed on to offspring. This is because body cells do not contribute genetic material to • A. each other. • B. sex cells. • C. non-mutant cells. • D. daughter cells. Answer: B

23. DNA Deoxyribonucleic Acid The primary function of DNA is to store and transmit genetic information. Molecules of DNA are composed of long chains of nucleotides. A nucleotide consists of a sugar, a phosphate group, and a nitrogenous base.

24. Genetic Code Codon-A sequence of three nucleotides that codes for a specific amino acid in the synthesis of protein

25. Chromosome Mutations Inversion-a chromosomal segment breaks off, flips around backward, and reattaches; a section of the chromosome was broken out and reinserted backwards

26. Chromosome Mutations Translocation-A mutation caused by a piece of DNA breaking away from its chromosome and becoming attached to a nonhomologous chromosome Ex. Prader Willi Syndrome

27. Chromosome Mutations Nondisjunction-a chromosome fails to separate from its homologue during meiosis A gamete will receive too many or too few copies of a chromosome. Ex. Down Syndrome-Have 47 chromosomes

28. Down’s Syndrome-Tri-somy 21

29. Human sex chromosome abnormalities

30. Poor beard growth Characteristic facial features Web of skin Nondisjunction in Sex Chromosomes Breast Development Constriction of aorta Under-developed testes Poor breast development Under developed ovaries Figure 8.22A Figure 8.22B

31. Substitution-one nucleotide replaces another Normal hemoglobin DNA Mutant hemoglobin DNA C A T T T C mRNA mRNA G A A G U A Normal hemoglobin Sickle-cell hemoglobin Glu Val Figure 10.16A

32. Nonsense Mutations • A genetic mutation that causes a codon that should code for a specific amino acid to be changed into a stop codon results in a shortened protein product and is known as a nonsense mutation.

33. Silent Mutations • A genetic mutation that does not result in a change in the amino acid sequence of the resulting protein is called a silent mutation.

34. Chromosome Mutations Deletion-the loss of a piece of a chromosome due to a breakage.

35. Chromosome Mutations Insertion-one or more nucleotides are added to a gene, which can also result in a frameshift mutation.

36. Normal gene U G C U U C A G A A U G A G G mRNA Met Lys Gly Protein Phe Ala Base substitution Frameshift mutation-A mutation in which remaining codons are grouped incorrectly Amoeba Sisters Mutations A A G A U G C A U G A G U U C Lys Met Phe Ser Ala Missing U Base deletion G G C G A C A U A U G A G U U Figure 10.16B Lys Ala His Met Leu

37. An organism's genotype describes its specific combination of alleles. For example, an Aa genotype is heterozygous for the A allele. An organism's phenotype describes a visible trait, such as tall height, brown eyes, or black fur. How does genotypic variation occur? A. Genotypic variation only occurs during binary fission. B. Genotypic variation occurs when alleles are randomly sorted during asexual reproduction. C. Genotypic variation only occurs when genetic mutations occur. • Genotypic variation occurs when alleles are randomly sorted during sexual reproduction. Answer: D Do Now

38. Tell which type of mutation the following are: • 1. CCTTGGA – CCTGGA • 2. CCTTGGA – CCGGTTA • 3. CCTTGGA – GGACCTT • 4. CCTTGGA – CATTGGA Do Now

39. Pedigree Pedigree-A diagram in which several generations of a family and the occurrence of certain genetic characteristics are shown Carrier-have one copy of the recessive allele but do not have the disease

41. Genetic Disorders and Traits Genetic Disorder-diseases or disabling conditions that has a genetic basis Polygenic Inheritance-traits that are influenced by several genes Complex characters-characters that are influenced strongly both by the environment and by genes

42. Genetic Disorders and Traits Multiple Alleles-genes with three or more alleles ABO Blood types

43. Genetic Disorders and Traits Incomplete Dominance-an individual displays a trait that is intermediate between the two parents Ex. RR=red Rr=pink rr=white X-Linked Traits-a gene that is carried on the X chromosome Ex. Colorblindness

44. Genetic Disorders and Traits Sex-Influenced Trait-males and females can show different phenotypes even when they share the same gene. Ex. Eye colors in fruit flies Single-Allele Traits-a single allele of a gene controls a single-allele trait

45. Detecting Genetic Diseases In humans, the risks of passing on a genetic disorder to one’s children can be assessed by: Analysis of a pedigree Genetic counseling-the process of informing a person or couple about their genetic makeup Prenatal testing

46. Genetic Counseling Genetic counseling is a process that: Helps identify parents at risk for having children with genetic defects Assists parents in deciding whether or not to have children Uses a family pedigree. Gene Therapy-a treatment in which a defective gene is replaced with a healthy gene.

47. Problem #1 While studying several generations of a particular family, a geneticist observed that a certain disease was found equally in males and females and that all children who had the disease had parents who also had the disease. The gene coding for this disease is probably Autosomal dominant.

48. Problem #2 If both parents carry the recessive allele that causes cystic fibrosis, the chance that their child will develop the disease is one in four