Chapter 5: Heritable Variation Among Individuals

Question 1

amino acids

Answer 1

the structural units that, among other functions, link together to form proteins

Question 2

nucleotide

Answer 2

the structural units that link together to form DNA (and RNA); each nucleotide includes a nucleobase

Question 3

nucleobase

Answer 3

[base] adenine, cytosine, guanine, thymine; uracil replaces thymine in RNA

Question 4

mutation

Answer 4

any change to the genomic sequence of an organism

Question 5

RNA

Answer 5

(ribonucleic acid) macromolecule essential to all known forms of life; differs from DNA in that it has a sugar ribose (not deoxyribose) and has uracil instead of thymine

Question 6

genes

Answer 6

segments of DNA whose nucleotide sequence codes for proteins, or RNA, or regulates the expression of other genes

Question 7

gene expression

Answer 7

the process by which information from a gene is transformed into a product

Question 8

sexual chromosome

Answer 8

chromosomes that pair during meiosis but differ in copy number between males and females; XX is female (homogametic) and XY is male (heterogametic)

Question 9

ploidy

Answer 9

the number of copies of unique chromosomes in a cell (n); normal human body cells are diploid in nature- only sex cells are haploid with 23 chromosomes

Question 10

transcription

Answer 10

the process that takes place when RNA polymerase reads a coding sequence of DNA and produces a complementary strand of RNA, called messenger RNA (mRNA)

Question 11

translation

Answer 11

the process that takes place when a strand of mRNA is decoded by a ribosome to produce a strand of amino acids

Question 12

transcription factors

Answer 12

proteins that bind to specific DNA sequences and act, in essence, like a light switch by turning all the sequences on or off simultaneously

Question 13

hormone

Answer 13

a molecular signal that flows from cells in one part of the body to cells in other parts of the body; hormones act directly or indirectly to alter expression of target genes

Question 14

RNA splicing

Answer 14

the process of modifying RNA after transcription but before translation, during which introns are removes and exons are joined together in a contiguous strand

Question 15

alternative splicing

Answer 15

the process of combining different subsets of exons together, yeilding different mRNA transcripts from a single gene

Question 16

genome

Answer 16

all of the hereditary information of an organism; the genome comprises the totality of the DNA, including the coding and noncoding regions

Question 17

microRNA

Answer 17

one group of RNAs that act as post-transcriptional regulators of gene expression; they bind to complementary sequences on specific mRNAs and can enhance or silence the translation of genes….the human genome encodes more than 1000 of these tiny RNAs

Question 18

pseudogenes

Answer 18

DNA sequences that resemble functional genes but have lost their protein-coding ability or are no longer expressed; pseudogenes often form after a gene has been duplicated, when one or more of the redundant copies subsequently lose their function

Question 19

mobile genetic elements

Answer 19

types of DNA that can move around in the genome; common examples include transposons (jumping genes) and plasmids

Question 20

vertical gene transfer

Answer 20

the process of receiving genetic material from an ancestor

Question 21

horizontal gene transfer

Answer 21

any process in which genetic material is transferred to another organism without descent; happens in microbes

Question 22

plasmids

Answer 22

molecules of DNA, found most often in bacteria, that can replicate independently of chromosomal DNA

Question 23

somatic mutations

Answer 23

mutations that affect the “body” of an organism and can influence phenotype but are not passed down because they are not in the sex cells

Question 24

germ-line mutations

Answer 24

mutations that do affect gametes and can be transmitted to offspring; they create the heritable variation that drives evolution

Question 25

allele

Answer 25

one of several alternative forms of the DNA sequence of the same locus

Question 26

meiosis

Answer 26

a form of cell division that occurs only in eukaryotes, in which the number of chromosomes is cut in half; meiosis gives rise to gametes and is essential to sexual reproduction

Question 27

genetic recombination

Answer 27

the exchange of genetic material between paired chromosomes during meiosis; recombination can form new combinations of alleles and is an important source of heritable variation

Question 28

genotype

Answer 28

the genetic makeup of an individual

Question 29

phenotype

Answer 29

the physical appearance of an individual brought to you by genotype

Question 30

genetic polymorphism

Answer 30

the simultaneous occurrence of two or more discrete phenotypes within a population

Question 31

polyphenic trait

Answer 31

a trait for which multiple, discrete phenotypes can arise from a single genotype depending on environmental circumstances

Question 32

dominant allele

Answer 32

alleles that produce the same phenotype whether they are paired with an identical allele or a different allele

Question 33

recessive allele

Answer 33

alleles that produce their characteristic phenotypes only when they are paired with an identical allele

Question 34

quantitative traits

Answer 34

measurable phenotypes that vary among individuals over a given range to produce a continuous distribution of phenotypes (complex traits)

Question 35

intron

Answer 35

a segment that doesn’t code for anything and is cut out

Question 36

exon

Answer 36

a segment that does contain useful information on coding for proteins and must be spliced together

Question 37

point mutation

Answer 37

one base in a DNA molecule is wrongex: sicle cell anemia caused by point mutation on gene that codes for hemoglobin; progeria; albinism; polydactyly

Question 38

silent mutation

Answer 38

amino acids are coded incorrectly but there is no resulting change

Question 39

replacement mutation

Answer 39

mutation that causes a different amino acid to be coded

Question 40

insertion or deletion

Answer 40

bases added or removed which causes a frame shift and a whole DNA strand is misread; results in a nonfunctional protein

Question 41

inversion

Answer 41

when the gene order is all flipped around

Question 42

genome duplication

Answer 42

everything is duplicated; can apply to a single gene, chromosome, or entire genome

Question 43

continuous variation

Answer 43

variation that has no limit on the value that can occur within a population (ex: height); results from differences in genotypes where multiple genes contribute to the expression of a trait