Textbook Notes (362,902)
Canada (158,096)
Psychology (9,565)
PSYB32H3 (1,174)
Chapter 2

PSYB20 Chapter 2.doc

5 Pages
Unlock Document

University of Toronto Scarborough
Chandan Narayan

Chapter 2 – Heredity and the Environment - genotype: particular set of genes that a person inherits from parents - phenotype: observable and measurable expression of individual’s physical and behavioural characteristics Process of Genetic Transmission - ovum: female germ cell (or egg)  largest human cell - sperm: male germ cell  smallest of all human cells - chromosomes: threadlike structures located in nucleus that carry genetic information that helps development - meiosis: process by which a germ cell divides to produce new germ cells with only half normal complement of chromosomes; thus , male and female germ cells each contain only 23 chromosomes so that when they unite the new organism will have 46 chromosomes, half from each parent - crossing over: process by which equivalent sections of homologous chromosomes switch places randomly, shuffling genetic information each carries - mitosis: process in which a body cell divides in two, first duplicating its chromosomes so that new, daughter cells contain usual 46 chromosomes o chromosome creates duplicate of self o splits into two cells o continues process  all daughter cells are same as parent - autosomes: 22 paired nonsex chromosomes - DNA: ladderlike molecule that stores genetic information in cells and transmits it during reproduction - gene: a portion of DNA that is located at a particular site on a chromosome and that codes for production of certain kinds of proteins o proteins serve for different characteristics Genetic Influences on Development - genes never work in isolation, but always in combination with environmental influences - Mendal  breeding pea plants - principle of segregation: each inherited trait comes from one’s parent as a separate unit (e.g. high, colour , etc) - principle of independent assortment: inheritance of various traits occurs independently of one another (colour has nothing to do with height) -  alleles: alternative form of a gene inherited one from mother and one from father o homozygous: if alleles from parents are same (e.g. both tall) o heterozygous: if alleles from parents are different (e.g. tall and short) o dominant: a more powerful allele in a heterozygous combination o recessive: weaker allele in a heterozygous combination o co-dominance: no dominant allele (blood type A and B) rd - Sex chromosomes: 23 pair of chromosomes; determine individuals gender and responsible for sex-related characteristicsfemales XX, male XY o x-linked genes: genes carried on X chromosome and may have no analogous genes on Y chromosome in males o hemophilia: disorder caused by X-linked recessive gene, in which blood fails to clot (found in males more than females)  female who inherits it will have normal clotting if second allele (inherited from other parent) does not code for hemophilia  if she is homozygous for recessive (aa) will blood be impaired  if male receive hemophilia allele on X chromosome greater danger of developing - gene modifier: genes that exert their influence indirectly by affecting expression of still other genes o e.g. early cataracts (also influenced by dominant gene) - sickle cell anemia: disorder caused by recessive gene, in which red blood cells become distorted when low in oxygen o causes fatigue, shortness of breath, severe pain, etc o Also interact with environment component. o Has survival value, cuz it is associated with resistance to malarial infection. - phenylketonuria (PKU): disease caused by recessive allele that fails to produce enzyme necessary to metabolize protein phenylalanine o Treatment should begin at birth o if untreated, can cause damage in nervous system and mental retardation - developmental disorders can be caused also by defects in entire chromosome o arise during process of meiosis o most cases aberration常 proves lethal and zygote spontaneously aborts o sometimes zygote able to survive baby with chromosome defect is born o e.g. down syndrome: chromosome abnormality suffering from physical and mental development; more susceptible to leukemia, heart disease, etc  occurs in set of chromosome number 21  have three chromosomes instead of two - turner syndrome: abnormality of sex chromosomes found in females o only have one X chromosome instead of XX because father’s sperm contained neither an X nor a Y chromosome when passed down o short, stubby fingers, normal intelligence, unable to socialize, etc o difficulty in interpreting emotional cues - Klinefelter’s syndrome: an extra X chromosome o females (XXX) cognitive abilities affected o  males (XXY) develop female characteristics (e.g. wide hips, breasts, cognitive deficit, etc) - fragile X syndrome: X chromosome appears to be pinched in some areas o occurs more in males, IQ scores between 30 and 55, etc Genetic Counselling and Genetic Testing Prenatal Diagnostic Techniques - Amniocentesis 羊膜穿刺 : technique for sampling fetal cells for indications of abnormalities o withdraw small amount of amniotic fluid from amniotic sac with needle o 16 week - chorionic villi sampling: sampling cells from chorionic villi o able to examine fetus’s chromosomes and genes for signs of disorder o Earlier than amniocentesis, 9 or 10 week - Huntington disease: deterioration of nervous system that begins in mid-adulthood o 50% chance of
More Less

Related notes for PSYB32H3

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.