Chapter 2 - Evolution, Genetics and Experience

Question 1

Dichotmous traits

Answer 1

traits that occur in one form or the other, never in Combination

Question 2

true-breeding lines

Answer 2

breeding lines in which interbred members always produce offspring with the same trait, eg brown seeds, generation after generation

Question 3

dominant trait

Answer 3

the trait of a dichotomous pair that is expressed in the phenotypes of heterozygous individuals

Question 4

recessive traits

Answer 4

the trait of a dichotomous pair that is not expressed in the phenotype of heterozygous individuals

Question 5

phenotype

Answer 5

an organisms observable traits

Question 6

genotype

Answer 6

that trait that it can pass on to offspring through genetic material

Question 7

alleles

Answer 7

two genes that control the same trait

Question 8

homozygous

Answer 8

organisms that possess two identical genes for a trait are said to be homozygous

Question 9

heterozygous

Answer 9

organisms that possess two different genes for a trait are said to be heterozygous

Question 10

chromosomes

Answer 10

threadlike structures in the cell nucleus that contain the genes, each chromosome is a DNA molecule

• they occur in matched pairs, and each species has a characteristic number of pairs in each of its body cells (23 pairs)

Question 11

gametes

Answer 11

egg cells and sperm cells

Question 12

meiosis

Answer 12

in meiosis, the chromosomes divide and one chromosome of each pair goes to each of the two gametes that results from cell division
> as a result, each gamete only has half the usual number of chromosomes

Question 13

zygote

Answer 13

a fertilized egg cell, it is produced in meiosis, when a sperm and egg cell combine during fertilization with the full complement of chromosomes

Question 14

genetic recombination

Answer 14

the meiotic process by which pairs of chromosomes cross over one another at random points, break apart and exchange genes

Question 15

mitosis

Answer 15

the process of cell division that produces cells with the same number of chromosomes as the parent cell

Question 16

DNA - deoxyribonucleic acid

Answer 16

the double-stranded, coiled molecule of genetic material,
each strand is a sequence of nucleotide bases attached to a chain of phosphate and deoxyribose
four nucleotide bases: adenine & thymine, guanine & cytosine

Question 17

DNA - replication

Answer 17

critical process by which the DNA molecule duplicates itself

Question 18

mutations

Answer 18

errors in duplication take the form of mutations—accidental alterations in individual genes.

Question 19

autosomal chromosomes

Answer 19

chromosomes that come in matched pairs

Question 20

sex-chromosomes

Answer 20

one exception to the autosomal chromosomes, pair of chromosomes that determines the individual’s sex

Question 21

sex-linked traits

Answer 21

traits that influenced by genes on the sex chromosomes

Question 22

Proteins

Answer 22

long chains of amino acids, they control the physiological activity of cells and are important components of cellular structure

Question 23

Enhancers

Answer 23

stretches of DNA whose function is to determine whether particular structural genes initiate the synthesis of proteins and at what rate

> they are found in the stretches of DNA that lack structural genes

Question 24

gene expression

Answer 24

the production of the protein specified by particular genes

Question 25

transcription factors

Answer 25

Proteins that bind to DNA and influence the extent to which genes are expressed > many of the description factors that control enhancers are influenced by signals received by the cell from the envrionment

Question 26

RNA (ribonucleic acid)

Answer 26

a molecule that is similar to DNA except that has the nucleotide base uracil and a phosphate and ribose backbone

Question 27

mRNA (messenger RNA)

Answer 27

a strand of RNA that is transcribed from DNA and then moves out of the cell nucleus where it is translated into a protein

Question 28

ribosomes

Answer 28

a structure in the cell's cytoplasm that translates strands of messenger RNA into proteins

Question 29

codon

Answer 29

each group of three consecutive nucleotide bases along the mRNA strand > instructs the ribosome add 1 of the 20 different kinds of amino acids

Question 30

transfer RNA

Answer 30

molecules of RNA that carry amino acids to ribosomes during protein synthesis; each kind of amino acid is carried b a different kind of transfer RNA molecule

Question 31

Human Genome Project

Answer 31

the international research effort to construct a detailed map of human chromosomes

Question 32

Epigenetics

Answer 32

the study of the all mechanisms of inheritance other than the genetic code and its expression

Question 33

DNA methylation

Answer 33

reaction that occurs when a methyl group attached to a DNA molecule; usually at cytosine > can either increase or decrease expression

Question 34

Histone remodeling

Answer 34

reaction that occurs when histones (proteins around which DNA is coiled) change their shape and therefore influence the adjacent DNA > can either increase or decrease expression

Question 35

RNA editing

Answer 35

some epigenetic effects regulate gene expression by acting on mRNA rather than genes

Question 36

transgenerational epigenetics

Answer 36

epigenetic mechanisms passed on to future generations > examines the transmission of experiences via epigenetic mechanisms across generations

Question 37

phenylperuvic acids

Answer 37

a substance that is found in abnormally high concentrations in the urine of those suffering from phenylketonuria

Question 38

Phenylketonuria (PKU)

Answer 38

a neurological disorder whose symptoms are vomiting, seizures, hyperactivity, hyper irritability, intellectual disability, brain damage and high levels of phenylpyruvic acid

Question 39

sensitive period

Answer 39

period early in life, during which a particular experience must occur to have a major effect on the development of a trait

Question 40

sensory phase

Answer 40

the first of the two phases of birdsong development, during which young birds do not sing but form memories of the adult songs they hear

Question 41

sensorimotor phase

Answer 41

the second of the two phases of birdsong development, during which juvenile birds progress from sub songs to adult songs

Question 42

monozygotic twins

Answer 42

develop from the same zygote and thus are genetically similar

Question 43

dizygotic twins

Answer 43

developed from two zygotes and thus are no more similar than any pair of siblings

Question 44

heritability estimate

Answer 44

a numerical estimate of the proportion of variability that occurred in a particular trait in a particular study and that resulted from genetic variation among the subjects in that study > tells us about the contribution of genetic differences to phenotypic differences among the participants in a study; they have nothing to say about the relative contributions pf genes and experiences to the development of individuals