Chapter 3 Flashcards

1
Q

DNA

A
  • deoxyribonucleic acid
  • the chemical composition of the molecules that contain the genes, which are the chemical instructions for cells to manufacture various proteins
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2
Q

chromosome

A
  • one of the 46 molecules of DNA (in 23 pairs) that virtually each cell of the human body contains and that, together contain all the genes
  • other species have more or fewer
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3
Q

gene

A
  • a small section of a chromosome; basic unit for the transmission of heredity
  • consists of a string of chemicals that provide instructions for the cell to manufacture certain proteins
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4
Q

allele

A
  • a variation that makes a gene different in some way from other genes for characteristics
  • many genes never vary; others have several possibilites
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5
Q

genome

A

-the full set of genes that are the instructions to make an individual member of a certain species

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6
Q

gamete

A

-a reproductive cell—that is, a sperm or ovum that can produce a new individual if it combines with a gamete from the other sex to make a zygote

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7
Q

zygote

A

-the single cell formed from the union of two gametes, a sperm and an ovum

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8
Q

genotype

A

-an organism’s entire genetic inheritance, or genetic potential

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9
Q

homozygous

A
  • referring to two genes of one pair that are exactly the same in every letter of their code
  • most genes are _______
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10
Q

heterozygous

A
  • referring to two genes of one pair that differ in some way
  • typically one allele has only a few base pairs that differ from the other member of the pair
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11
Q

23rd Pair

A
  • the chromosome pair that determines sex in humans
  • the other 22 pairs are autosomes–inherited equally by males and females
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12
Q

XX

A
  • a 23rd chromosome pair that consists of two X-shaped chromosomes, one each from the mother and the father
  • ___zygotes become females
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13
Q

XY

A
  • a 23rd chromosome pair that consists of an X-shaped chromosome from the mother and a Y-shaped chromosome from the father
  • ___zygotes become males
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14
Q

stem cells

A

-cells from which any other specialized type of cell can form

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15
Q

monozygotic (MZ) twins

A
  • twins who originate from one zygote that splits apart very early in development
  • aka identical twins
  • other monozygotic multiple births (such as triplets and quadruplets) can occur as well
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16
Q

dizygotic (DZ) twins

A
  • twins who are formed when two separate ova are fertilized by two separate sperm at roughly the same time
  • aka fraternal twins
17
Q

ART

A
  • assisted reproductive technology
  • a general term for the techniques designed to help infertile couples conceive and then sustain a pregnancy
18
Q

IVF

A
  • in vitro fertilization
  • fertilization that takes place outside a woman’s body (as in a glass laboratory dish)
  • procedure involves mixing sperm with ova that have been surgically removed from the woman’s ovary–if a zygote is produced, it is inserted into a woman’s uterus, where it may implant and develop into a baby
19
Q

phenotype

A

-the observable characteristics of a person, including appearances, personality, intelligence, and all other traits

20
Q

polygenic

A

-referring to a trait that is influenced by many genes

21
Q

multifactorial

A

-referring to a trait that is affected by many factors, both genetic and environmental, that enhance, halt, shape, or alter the expression of genes, resulting in a phenotype that may differ markedly from the genotype

22
Q

epigenetic

A

-referring to environmental factors that affect genes and genetic expression–enhancing, halting, shaping, or altering the expression of genes and resulting in a phenotype that may differ markedly from the genotype

23
Q

Human Genome Project

A
  • an international effort to map the complete human genetic code
  • essentially completed in 2001, though analysis is ongoing
24
Q

dominant-recessive pattern

A

-the interaction of a heterozygous pair of alleles in such a way that the phenotype reflects one allele (dominant gene) more than the other (recessive gene)

25
carrier
- a person whose genotype includes a gene that is not expressed in the phenotype - the carried gene occurs in half of the carrier's gametes and thus is passed on to half of the carrier's children - if such a gene is inherited from both parents, the characteristic appears in the phenotype
26
X-linked
-a gene carried on the X chromosome ---if a male inherits an X-linked recessive trait from his mother, he expresses that trait because the Y from his father has no counteracting gene ---females are more likely to be carriers of X-linked traits but are less likely to express them
27
copy number variations
-genes with various repeats or deletions of base pairs
28
heritability
-a statistic that indicates what percentage of the variation in a particular trait within a particular population, in a particular context and era, can be traced to genes
29
down syndrome
- a condition in which a person has 47 chromosomes instead of the usual 46, with 3 rather than 2 chromosomes at the 21st site - people with Down syndrome typically have distinctive characteristics, including unusual facial features, heart abnormalities, and language difficulties - aka trisomy-21
30
fragile X syndrome
- a genetic disorder in which part of the X chromosome seems to be attached to the rest of it by a very thin string of molecules - the cause is a single gene that has more than 200 repetitions of one triplet
31
genetic counseling
-consultation and testing by trained experts that enable individuals to learn about their genetic heritage, including harmful conditions that they might pass along to any children they may conceive
32
PKU
- a genetic disorder in which a child's body is unable to metabolize an amino acid called phenylalanine - unless the infant immediately begins a special diet, the resulting buildup of phenylalanine in body fluids causes brain damages, progressive mental retardation, and other symptoms