Exam 1: Chapter 3 Vocab

Question 1

gamete

Answer 1

a reproductive cell, sperm or egg in humans

Question 2

zygote

Answer 2

the single cell formed from the union of two gametes (a sperm + an ovum)

Question 3

gene

Answer 3

a small section of a chromosome; the basic unit for the transmission of heredity; consists of a string of chemicals that provide instructions for the cell to manufacture certain proteins

Question 4

chromosome

Answer 4

one of the 46 molecules of DNA (in 23 pairs) that virtually each cell in the human body contains and that, together, contain all genes

Question 5

human genome project

Answer 5

an international project to map the complete human genetic code

Question 6

the twenty third pair

Answer 6

the chromosome pair that, in humans, determines sex. The other 22 pairs are autosomes, inherited equally by males and females

Question 7

monozygotic twins

Answer 7

twins who originate from 1 zygote that splits early in development. Other monozygotic multiple births can also occur.

Question 8

dizygotic twins

Answer 8

twin formed when 2 separate ova are fertilized by 2 separate sperm at roughly the same time

Question 9

genotype

Answer 9

an organisms entire genetic inheritance or genetic potential

Question 10

phenotype

Answer 10

the obervable characteristics of a person including appearance, personality, intelligence, and all other traits,

Question 11

polygenetic traits

Answer 11

a trait that is controlled by multiple non allelic genes

include height, skin color, eye color, intelligence, and susceptibility to certain diseases.

Question 12

x-linked recessive genes

Answer 12

a gene carried on the X chromosome. if a male inherets an x-linked recessive trait from his mother, he expresses that trait because the Y gene from his father has no counteracting gene. Females are more likely to be carriers, but less likely to express

Question 13

what is a multifactorial trait?

Answer 13

a trait controlled by multiple factors such as genes and environment

ex.) human height: controlled by genetics but also nutrition plays a role

Question 14

trisomy 21

Answer 14

aka down syndrome
a condition in which a person has 47 chromosomes instead of the usual 46 with 3 rather than 2 on the 21st pair. People with down syndrome typically have distinctive characteristics including facial features, heard abnormalities and language difficulties

Question 15

autosomes:

Answer 15

22 of the 23 chromosome pairs

Question 16

mitosis

Answer 16

the process of duplication and division in which each new cell contains 23 chromosome pairs=46 chromosomes just before cell division, the 46 duplicate and then divide to create new cells

Question 17

read the section in the textbook on “chromosomal and genetic problems”

Answer 17

(page 78 :))

Question 18

what are the different post conception tests

Answer 18

1. preimplantation testing
2. testing for pregnancy associated with PAPPA
3. alpha-fetoprotein (AFP) assay
4. sonogram (ultrasound)
5. chorionic villi sampling
6. amniocentesis

Question 19

pre-implantation testing

Answer 19

after in vitro fertilization, one cell is removed from each zygote at the 4 or 8 cell stage and analyzed

risks and concerns:
-not entirely accurate
-requires surgery, IVF, and rapid assessment
-this delays implantation and reduces the likelihood of successful birth
-used only when couples are at high risk of known, testable genetic disorders

Question 20

tests for Pregnancy Associated with Plasma Protein (PAPPA) and human chronic gonadotropin

Answer 20

blood tests are usually done at 11 weeks to test for those substances

risks and concerns:
-indicate normal pregnancy, but false positive and negatives can sometimes occurinq

Question 21

Alpha feto-protein assay

Answer 21

the mothers blood is tested for the level of alpha feto-protein, now usually done at mid pregnancy; often combined with other blood tests and repeat sonogram

risks and concerns:
indicate neural tube defects, multiple embryos (both cause AFP) Normal levels change each week; interpretation requires accurate date of conception

Question 22

sonogram (ultrasound)

Answer 22

high frequency sound waves are used to produce a ‘picture’ of the fetus as early as 8 weeks. More accurate later in pregnancy to detect less apparent problems, to confirm earlier suspicions, and anticipate birth complications

risks and concerns:
reveals problems such as small head or other body malformations, excessive fluid accumulating in the brain, down syndrome, and several other diseases

estimates fetal age and reveals multiple fetuses, placental position, useful in every pregnancy, sometimes sex is apparent

no known risks unlike x-rays

Question 23

chorionic villi sampling

Answer 23

a sample of the chorion (part of the placenta) in obtained (via sonogram and syringe) at about 10 weeks and analyzed. The cells of the placenta are genetically identical to the cells of the fetus, this can indicate genetic and fetal abnormalities

risks and concerns:
can cause spontaneous abortion (only in 1%)
provides the same information as amniocentesis but can be performed earlier

Question 24

amniocentesis

Answer 24

about half an ounce of the fluid inside the placenta is withdrawn at about 16 weeks. The cells are cultured and analyzed.

risks and concerns:
-spontaneous abortion cause by the syringe, but is very rare .05%)
-detects chromosomal abnormalities and other prenatal problems
-the amniotic fluid also reveals the sex of the fetus
-done later in pregnancy and takes about a week for results to develop

Question 25

info on gamete selection

Answer 25

-ova and sperm are screened to select ones that are particularly free of problems
-requires IVF but avoids the rejection of a viable zygote
-every gamete (and every human) carries genes for some harmful conditions, so gamete selection is only useful in particular conditions are likely and genetic tests are accurate.