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test two Flashcards

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AP® Biology flashcards
1
Q

chromosome

A

a tightly coiled combination of a DNA molecule (which contains genetic information for the organism) and specialized proteins called histones; found in the cell nucleus

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2
Q

gene (chap. 19)

A

a specific segment of the DNA that directs the synthesis of a protein, which in turn plays a structural or functional role within the cell; determines the expression of a particular characteristic or trait

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3
Q

somatic cells

A

all cells except eggs or sperm; have 46 chromosomes (23 pairs)

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4
Q

gametes

A

a mature haploid male or female germ cell which is able to unite with another of the opposite sex in sexual reproduction to form a zygote

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5
Q

diploid

A

any cells with two of each kind of chromosome; 2n chromosomes where n=23

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6
Q

haploid

A

have only one member of each homologous pair of chromosomes; n chromosomes where n=23

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7
Q

autosomes

A

determine the expression of most of a person’s inherited characteristics; all chromosomes except for sex chromosomes

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8
Q

sex chromosomes

A

one of the 23 pairs of chromosomes that determines whether a person is male (XY) or female (XX)

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9
Q

cytokinesis

A

division of the cytoplasm, beginning at the end of mitosis or meiosis, during telophase

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10
Q

karyotype

A

an arrangement in which the chromosomes are numbered from largest to smallest; they can be checked for irregularities in number or structure of chromosomes

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11
Q

synapsis

A

separated homologous chromosome pairs line up next to one another (during prophase 1)

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12
Q

crossing over

A

corresponding pieces of chromatids of maternal and paternal homologues are exchanged during synapsis (prophase I) when the homologues are aligned side by side of one chromosome

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13
Q

trisomy

A

a condition where there are three representatives of one chromosome

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14
Q

monosomy

A

one representative of a particular chromosome in a cell

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15
Q

genes (chap. 20)

A

direct the synthesis of a specific protein that can play either a structural or a functional role in the cell

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16
Q

trait

A

a phenotypically expressed characteristic; gene-determined protein can influence whether a certain trait or characteristic will develop

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17
Q

alleles

A

different versions of a gene; produce different versions of the trait they determine

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18
Q

genotype

A

the precise set of alleles a person possesses for a given trait or traits

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19
Q

phenotype

A

the observable physical trait or traits of an individual

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20
Q

carrier

A

someone who displays the dominant phenotype but is heterozygous for a trait and can, therefore, pass the recessive allele to descendants

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21
Q

complete dominance

A

a situation in which a heterozygous individual exhibits the trait associated with the dominant allele but not that of the recessive allele; the dominant allele produces a functional protein and the protein’s effects are apparent, but the recessive allele produces a less function protein, or none at all, and its effects are not apparent

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22
Q

co-dominance

A

in a heterozygous genotype, both alleles produce functional proteins; the effects of both alleles are apparent in the heterozygous phenotype; for example, blood type AB

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23
Q

pleiotropy

A

an example of incomplete dominance; one gene leading to many effects

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24
Q

incomplete dominance

A

the expression of a trait in a heterozygous individual is somewhere between the expression of the trait in a. homozygous dominant individual and the expression of the trait in a homozygous recessive individual

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25
Q

multiple alleles

A

when three or more forms of a given gene exist

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26
Q

polygenic inheritance

A

the involvement of two or more genes, often on different chromosomes, in producing a trait; the more genes involved, the smoother the gradation and the greater the extremes of trait expressions

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27
Q

DNA (3)

A

deoxyribose nucleic acid; a double stranded molecule resembling a ladder that is gently twisted to form a spiral called a double helix; each of the sides of the ladder is made from a string of repeated subunits called nucleotides

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28
Q

nucleotides

A

composed on three subunits, including one sugar, one phosphate and one nitrogenous base (adenine, guanine, thymine, cytosine)

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29
Q

complementary base pairing

A

rules bases follow when attaching to one another. in DNA, adenine pairs only with thymine (A-T) and cytosine pairs only with guanine (C-G). in RNA, adenine pairs only with uracil (A-U) and cytosine pairs only with guanine (C-G)

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30
Q

codons

A

the “words” in the genetic code; sequences of three bases on mRNA that specify 1 of the 20 amino acids or the beginning/end of the protein chain

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31
Q

genetic code

A

the “language” of genes that translates the sequence of bases in DNA into the specific sequence of amino acids in a protein

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32
Q

DNA replication (6 steps)

A

the copying process; begins when an enzyme breaks the weak hydrogen bonds that hold together the paired bases that make up nucleotide strands of the double helix, thereby unzipping the strands; the nitrogenous bases on the separated regions of each strand are temporarily exposed, serving as a template for new strands. free nucleotide bases can then attach to complementary bases on the open DNA strands. DNA polymerase links sugars + phosphates to new nucleotides and form new strands

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33
Q

RNA (6)

A

ribonucleic acid; single stranded with ribose as the sugar; contains uracil instead of thymine. functions primarily in cytoplasm. DNA directs the synthesis of RNA which, in turn, directs the synthesis of a polypeptide or a protein; three types of RNA

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34
Q

mRNA

A

messenger RNA; carries DNA’s instructions for synthesizing a particular protein from the nucleus to the cytoplasm

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35
Q

tRNA

A

transfer RNA; specialized to bring a specific amino acid to where it can be added to a polypeptide that is under construction

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36
Q

rRNA

A

ribosomal RNA; combines with proteins to form ribosomes

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37
Q

promoter

A

the signal to start transcription; given by a specific sequence of bases on DNA (the promoter)

38
Q

RNA polymerase

A

enzyme that binds with the promoter on DNA and then moves along the DNA strand, opening up the DNA helix in front of it and then aligning the appropriate RNA nucleotides and linking them together

39
Q

transcription

A

first step of converting the DNA message to a protein; copies the message as RNA
(1) unwind/unzip specific region of DNA to be copied
(2) unwound DNA strand serves as template; RNA nucleotides pair with complementary bases
(3) newly formed strand of RNA (RNA transcript) released from the DNA
(4) DNA closes again

40
Q

translation

A

three stages
(1) initiation - major players in the protein synthesis come together (mRNA, tRNA, and ribosomal subunits)
(2) elongation - occurs as enzymes in the ribosome link the amino acids, forming a growing chain of amino acid (polysome: cluster of ribosomes simultaneously translating the same mRNA)
(3) termination - occurs when a stop codon moves into the ribosome (stops process of translation)

41
Q

non-disjunction

A

the failure of homologous chromosomes to separate during meiosis I or of sister chromatids to separate during meiosis II; nondisjunction results in too many or too few chromosomes in a cell

42
Q

trisomy 21

A

down syndrome; three copies of chromosome 21; moderate to severe mental impairment, short stature, or shortened body parts and distinct facial features.

43
Q

klinefelter syndrome

A

observed in males who are XXY

44
Q

jacob syndrome

A

a male with two y chromosomes (XYY)

45
Q

stages of the cell cycle

A

two major phases: interphase and cell division (mitosis or meiosis)

46
Q

stages of mitosis

A

prophase, metaphase, anaphase, telophase

47
Q

stages of meiosis

A

meiosis I - prophase I, metaphase I, anaphase I, and telophase I
meiosis II - prophase II, metaphase II, anaphase II, and telophase II

48
Q

mitosis vs meiosis

A

mitosis: involves one cell division, produces two diploid cells, occurs in somatic cells, results in growth and repair, no exchange of genetic material, daughter cells are genetically similar
meiosis: involves two cell divisions, produces up to four haploid cells, occurs only in ovaries and testes during formation of gametes (egg and sperm), results in gamete (egg and sperm) production, parts of chromosomes are exchanged in crossing over, daughter cells are genetically dissimilar

49
Q

where/when does mitosis occur

A

occurs in somatic cells (all cells except sex cells), occurs during cell division (after interphase in the cell cycle)

50
Q

where/when does meiosis occur

A

meiosis occurs in sex cells (sperm and eggs) and occurs during cell division (after interphase in the cell cycle)

51
Q

dominant vs recessive alleles

A

dominant allele: when the effects of a certain allele is present
recessive alleles: an allele whose effects are masked in the heterozygous condition

52
Q

homozygous vs heterozygous alleles

A

homozygous: individuals with two copies of the same allele of a gene
heterozygous: individuals with different alleles of a given gene

53
Q

genotype vs phenotype

A

genotype: the precise set of alleles a person possesses for a given trait
phenotype: the observable physical trait(s)

54
Q

outline of transcription

A

the process of producing RNA from a DNA template

55
Q

outline of translation

A

converts the RNA to the language for the protein

56
Q

turner syndrome

A

occurs in individuals who have only a single X chromosome (XO)

57
Q

triple-x syndrome

A

a female with three x chromosomes (XXX)

58
Q

cri-du-chat

A

the loss of a small region near the tip of chromosome 5; condition is not fatal but causes mental impairment as well as distinct facial features

59
Q

fragile x syndrome

A

abnormally long sequence of repeats caused by duplication makes the x chromosome fragile and easily broken

60
Q

interphase

A

the period of the cell cycle between cell divisions; accounts for most of the time that elapses during a cell cycle. during interphase, the cell carries out its functions and grows; preps for cell divisions. dna and organelles are duplicated. consists of G1, S and G2

61
Q

G1

A

a time of major growth before DNA synthesis begins

62
Q

S

A

the time during which DNA is synthesized (replicated)

63
Q

G2

A

a time of growth after DNA is synthesized and before mitosis begins

64
Q

mitosis - prophase

A

chromosomes condense

65
Q

mitosis - metaphase

A

chromosomes (consisting of two chromatids) line up at equatorial plate

66
Q

mitosis - anaphase

A

the attachments between sister chromatids break

67
Q

mitosis - telophase

A

new nuclei form, each with two complete sets of chromosomes; cytokinesis divides cell into two daughter cells

68
Q

meiosis I - prophase I

A

chromosomes condense, synapsis occurs (homologous chromosomes pair and become perfectly aligned with one another), crossing over takes place

69
Q

meiosis I - metaphase I

A

homologous pairs of chromosomes line up at the midline of the cell; spindle fiber from one pole attaches to one member of each pair while spindle fiber from opposite pole attaches to the homologue.

70
Q

meiosis I - anaphase I

A

homologous pairs of chromosomes separate and move to opposite ends of the cell; each homologue still consists of two chromatids

71
Q

meiosis I - telophase I

A

one member of each homologous pair is at each pole; cytokinesis occurs and forms two haploid daughter cells. each chromosome still consists of two chromatids

72
Q

meiosis II - prophase II

A

chromosomes condense again, occurs in both daughter cells

73
Q

meiosis II - metaphase II

A

chromosomes line up at the midline of the cell

74
Q

meiosis II - anaphase II

A

centromeres of sister chromatids separate, chromatids of each pair are now called chromosomes chromosomes move to opposite poles

75
Q

meiosis II - telophase II

A

one complete set of chromosomes is located at each pole; cytokinesis occurs in both daughter cells, forming four haploid daughter cells

76
Q

role of tRNA, mRNA, rRNA, ribosomes, codons, and anticodons in translation

A

codons: three base sequence on mRNA
mRNA: product of transcription, takes the DNA info in the sequence of codons from the nucleus to the cytoplasm (where translation occurs)
tRNA: converts message carried by mRNA into a particular sequence of amino acids; enzymes ensure tRNA binds with correct amino acid; brings amino acid to correct location on mRNA strand
anticodon: a three-base sequence on tRNA that is complementary to the mRNA codon; binds to mRNA codon and specific amino acid is added to growing polypeptide chain
ribosomes: two subunits (rRNA and protein); bring tRNA bearing an amino acid close enough to mRNA to react (permit the alignment of codon & anticodon)
rRNA: combine with protein to make ribosome

77
Q

products of transcription

A

single stranded RNA molecule (the RNA transcript) –> RNA does not remain bonded to DNA template but instead leaves (mRNA)

78
Q

independent assortment

A

the positioning of homologous maternal and paternal chromosomes with respect to poles of the cell is random.
members of each homologous pair orient independently of other pairs during metaphase I

79
Q

deletion in chromosomes

A

loss of a piece of chromosome, most common deletion occurs when the tip of a chromosome breaks off; example is cri-du-chat syndrome

80
Q

duplication in chromosomes

A

addition of a piece of a chromosome; example is fragile x syndrome in which there is a duplication of a region on the x chromosome

81
Q

where/when does DNA replication occur

A

where: the nucleus
when: occurs in S phase during interphase

82
Q

what triggers the process of DNA replication to occur?

A

enzyme (DNA helicase) breaks hydrogen bonds that hold together the paired bases

83
Q

what is the role of a promoter/polymerase in DNA replication?

A

DNA polymerase: links the sugars and phosphates once free nucleotides have matched to form the two new strands (matches nucleotides to build daughter cells)
promoter:

84
Q

what are mutations in DNA replication?

A

changes in the DNA; passed to offspring only when they occur in a gamete. can be chromosomal or gene
chromosomal - occur when whole sections of chromosomes are duplicated or deleted
gene - changes in the order of nucleotides in DNA; those involving insertion or deletion of nucleotides can greatly change resulting protein

85
Q

where does transcription occur

A

in the nucleus

86
Q

where does translation occur

A

in the cytoplasm

87
Q

products of translation

A

protein; genetic info in mRNA is decoded into specific amino acid sequences that produce polypeptides or proteins

88
Q

steps of elongation (translation)

A

(1) a tRNA with the appropriate anticodon pairs with the next codon on mRNA
(2) enzymes link the amino acids
(3) the tRNA in the first binding site leaves the ribosome. the ribosome moves along the mRNA, exposing the next codon. enzymes link the amino acids. the process gets repeated many times

89
Q

steps of termination (translation)

A

(1) the stop codon moves into the ribosome
(2) release factors cause the release of the newly formed polypeptide and the separation of the ribosomal subunits and the mRNA

90
Q

when DNA is tightly coiled, genes are

A

not expressed

human biology (2 decks)

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