General Biology BIO 1050 - 02
Popular in General Biology
Popular in Biology
This 6 page Class Notes was uploaded by Kara Fields on Monday April 4, 2016. The Class Notes belongs to BIO 1050 - 02 at East Carolina University taught by Dr. Whelan in Spring 2016. Since its upload, it has received 11 views. For similar materials see General Biology in Biology at East Carolina University.
Reviews for General Biology
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 04/04/16
Biol 1050 SPRING 2016 Dr. Whelan More Genetics I. More complicated inheritance patterns A. Do Mendel’s principles explain all patterns of genetic inheritance? Incomplete dominance Codominance Multiple alleles Polygenic Pleiotropic genes Mendel didn’t know about these things. Was spot on with his findings, though. Just not in enough detail. a. What role does the environment play in human characteristics? How much sun that you receive. Or how little that you receive. If someone in your household smokes. II. Sex Determination A. Human sex chromosomes a. What are the male sex chromosomes? X and X b. What are the female sex chromosomes? X and Y c. Explain why fathers determine the sex of their offspring, instead of mothers. Because they hold the sperm. The sperm are either an X chromosome or a Y chromosome. If the Y chromosome reaches the egg first, it will be a male. If the X chromosome reaches the egg first, it will be a female. B. Do all animals have the same system of sex determination? 1 Biol 1050 SPRING 2016 Dr. Whelan No. Most have a different amount of chromosomes than humans do. III. Sexlinked genes A. What is a sexlinked gene? Any gene located on a sex chromosome is called a sexlinked gene B. Do both sex chromosomes have the same number of genes? X has many more genes than Y C. Genes on the X chromosome a. How many alleles do females carry for a trait carried on the X chromosome? Females have the dominant allele. They carry 2 alleles for trait. b. How many alleles do males carry for a trait carried on the X chromosome? Males have the recessive allele. Male are more common for the X linked disorders. They only have 1 X chromosome. They carry 1 allele for trait. D. Describe sexlinked disorders. Some disorders result from recessive alleles on X chromosomes Disorders expressed more by men than by women a. What are some examples of sexlinked disorders? hemophilia = disease where blood won’t clot correctly redgreen color blindness b. Example 2 Biol 1050 SPRING 2016 Dr. Whelan i) What genotypes are possible for a sexlinked trait in a female? What phenotypes correspond to each of these possible genotypes in a female? Female can have: X X B X X b X X b Homozygous Dominant. Normal vision… Heterozygous. Normal Vision… Homozygous Recessive. Colorblind… ii) What genotypes are possible for a sexlinked trait in a male? What phenotypes correspond to each of these possible genotypes in a male? Male can have: B X Y b X Y IV. Pedigrees A. How are human genetic disorders usually studied since we can’t do experiments controlling who mates with whom? A pedigree is a useful tool to document a trait of interest across multiple generations of family members. a. What is the symbol for a female in a pedigree? A male? A circle for females. A square for males. b. What is the symbol for a marriage or mating? A straight line connecting two people. c. How are offspring shown? A straight line going down from the mom and dad’s connecting line. d. How are people with a genetic disorder shown? 3 Biol 1050 SPRING 2016 Dr. Whelan A shaded square or circle. e. How can you tell if a trait is recessive or dominant on a pedigree? You have to look at the other parent and the offspring. You can’t tell just by looking at the pedigree. V. Disorders caused by the presence of an abnormal number of chromosomes A. Background a. What causes disorders? Many genetic diseases caused by alleles at one or more genes But other disorders caused by having an abnormal number of chromosomes b. What causes abnormal chromosome numbers? caused by a nondisjunction c. What is a nondisjunction? = members of a chromosome pair fail to separate in meiosis d. What causes a nondisjunction? Don’t know what causes. e. What is the result of a nondisjunction? Gametes with abnormal #’s of chromosomes. f. What happens if a sperm fertilizes an egg with an abnormal chromosome number? It will cause a syndrome such as Turner Syndrome, Klinefelter’s Syndrome, “Super Males”, or “Metafemales”. 4 Biol 1050 SPRING 2016 Dr. Whelan g. Can nondisjunctions lead to abnormal chromosome numbers in autosomes, sex chromosomes, or both? Sex Chromosomes. B. Abnormal numbers of autosomes a. What happens to a human embryo born with an abnormal # of autosomes? Usually miscarried before birth. b. What is a syndrome? Those that survive have a characteristic set of symptoms= a syndrome. c. Down syndrome have an extra chromosome 21 also called trisomy 21 d. How does the age of the mother influence the likelihood of a baby having Down syndrome? Don’t know why risk increases with mom’s age… e. Explain what we know about why the likelihood of Down syndrome increases with the mother’s age. But meiosis begins in ovaries before birth but does not continue until time of ovulation Longer time lag means increased chance for errors C. Abnormal numbers of sex chromosomes a. Do offspring with abnormal numbers of sex chromosomes usually survive? 5 Biol 1050 SPRING 2016 Dr. Whelan Yes. b. Figure 631 in textbook c. Describe the general rules for which chromosomes produce “maleness” versus what creates “femaleness”. In general: 1 Y chromosome is enough to produce “maleness”, even if several X’s are present Absence of a Y chromosome results in “femaleness” 6
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'