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BIO 125 Struct. of Living Organisms > Exam 2: Key Terms > Flashcards

Exam 2: Key Terms Flashcards

1
Q

allele

A

different versions of a gene

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2
Q

codominance

A

the effect of both alleles is equally visible in the phenotype of the hetero zygote

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3
Q

dihybrid

A

individuals that are heterozygous for two traits

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4
Q

dominant allele

A

the allele that exerts a controlling influence on the phenotype in a gene heterozygote is said to be dominant

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5
Q

epistasis

A

when the phenotype effect of the alleles of one gene depends on the presence of certain alleles for another, independently inherited gene

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6
Q

gene

A

a piece of DNA that codes for genetic traits and are located on chromosomes

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7
Q

genetic cross

A

controlled mating experiment performed to examine how a particular trait is inherited

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8
Q

genetic trait

A

inherited characteristic of an organism that can be observed or detected in some manner

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9
Q

genotype

A

the allelic makeup of that individual with respect to the specified genetic trait

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10
Q

heterozygote

A

an individual whose genotype consists of two different alleles for a given phenotype

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11
Q

homozygote

A

an individual whose genotype consists of two copies of the same allele

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12
Q

hybrid

A

the offspring resulting from a cross between to purebreds (ex. mule & donkey)

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13
Q

incomplete dominance

A

produces an intermediate phenotype in the heterozygote (white & red make pink)
- no single allele completely dominates over the other and the heterozygote displays an “inbetween” phenotype

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14
Q

law of independent assortment

A

when gametes form, the alleles of a particular gene segregate during meiosis independetly of the alleles of other genes - located on separate chromosomes

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15
Q

law of segregation

A

the two copies of a gene are separated during meiosis and end up in different gametes

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16
Q

phenotype

A

the display of a particular version of a genetic trait in a specific individual

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17
Q

pleiotropy

A

a single gene influences two or more distinctly different traits (albinism)

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18
Q

recessive allele

A

an allele that has no effect on the phenotype when paired with a dominant allele in a heterozygote is said to be recessive

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19
Q

autosome

A

all chromosomes that don’t determine sex

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20
Q

chromosome theory of inheritance

A

all genes are located on chromosomes

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21
Q

crossing over

A
  • happens during meiosis
  • reciprocal exchange of segments of non sister chromatids
  • only thing that can unlink gene
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22
Q

deletion in relation to chromosomes

A

occurs when a piece of a chromosome breaks off and is lost (chromosomes with deleted will be shorter. only have 1 copy of gene)

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23
Q

duplication

A

a chromosome becomes longer because it ends up with two copies of a particular chromosome fragment (piece copied more than once)

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24
Q

genetic carrier

A

individuals that are heterozygous for a recessive disorder Ww

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25
genetic linkage
genes that are positioned close to each other on the same chromosome tend to be inherited together -located on the same chromosome
26
inversion
occurs when a fragment of a chromosome breaks off and returns to the correct place on the original chromosome, but with the genetic loci in reverse order (expresses the gene backward)
27
locus
the physical location of a gene on a chromosome
28
random fertilization
any sperm can fertilize any egg, so that the gentic combinations possible for a single fertilization is huge
29
sex chromosome
chromosomes that determine the sex (XY --> male XX --> female)
30
sex linked
genes found only on the X or Y chromosome
31
somatic mutation
occur in any cell of the body except the germ line cells (sperm & egg) and cannot be passed onto children
32
SRY gene
- carried by the Y chromosome - a master gene that causes other genes located on autosomes to produce male sexual characteristics , without it develops as a female
33
test cross
a cross in which one parent is known to be a recessive homozygote and allows geneticists to evaluate whether an individual with a dominant phenotype is homo or heterzygote
34
translocation
occurs when a broken piece from one chromosome becomes attached to a different, nonhomologous chromosome (cross over event of different chromosomes)
35
trisomy
when a person inherits three copies of a chromosome (down syndrome --> chromosome 21)
36
independent assortment of chromosomes
creates new combinations of alleles through the random distribution of maternal and paternal chromosomes into gametes during meiosis
37
base pair
G-C A-T(U) -two nitrogenous bases held together by hdrogen bonds in a DNA molecule
38
DNA polymerase
is the enzyme that connects nucleotides to make the new strand, using the old strand as the template (proofreads and mismatches are detected and removed -enzyme involved in DNA replication
39
DNA repair
1. recognition 2. removal 3. replacement
40
genome
all the DNA based information in its chromosomes
41
housekeeping gene
play an essential role in the maintenance of cellular activities in all kinds of cells
42
non coding DNA
DNA that does not code for any kind of functional RNA
43
ribosome
where proteins are made directed by mRNA molecules
44
semiconservative replication
one old strand (template strand) is retained, in each new double helix and used as a template for a new complementary strand
45
anticodon
mRNA binding site
46
frameshift
insertion or deletion of one or two nucleotides
47
deletion in relation to DNA
when a base is inserted into or deleted from a DNA sequence
48
exon
segments of genes that actually code for amino acids
49
insertion
when a base is inserted into a DNA sequence
50
messenger RNA
delivers the genetic information, or instructions, from DNA to the ribosomes, where proteins are made
51
gene promoter
sections of a gene/dna that function as an off/on switch for transcription.
52
genetic code
the nucleotide triplets of DNA and RNA molecules that carry genetic information in living cells.
53
intron
stretches of DNA that do not code for amino acid sequences of proteins and must be spliced out
54
translation
process by which ribosomes covert the genetic information in mRNA into proteins
55
regulatory DNA
can activate or inactive gene expression
56
regulatory protein
interact with the environment and with regulatory DNA to promote or repress gene transcription
57
Ribosomal RNA
assists in making the covalent bonds that liknk amino acids together to make a protein
58
RNA Polymerase
synthesizes RNA using one strand of the DNA as a template | -binds to a segment of DNA near the beginning of a gene
59
DNA fingerprinting
is the process of identifying DNA unique to a species or individual
60
substitution
one base is substituted for another in the DNA sequence of the gene
61
template strand
one of the two DNA strands is used as a template
62
transfer RNA
transports the correct amino acid to ribosome, using the information encoded in the mRNA
63
adult stem cell
undifferentiated cells in the adult body that produce only a limited number of different cell types
64
RNA interference
selectively blocks the expression of a given gene
65
directional selection
when individuals at one extreme of an inherited phenotypic trait have an advantage over other individuals in the population (one side)
66
DNA hybridzation
target DNA is cut into fragments by restriction enzymes and converted to a single stranded form by treatments that break the hydrogen bonds holding the two strands together
67
DNA miccroarray
consists of a solid support, the size of a microscope slide, on which known DNA sequences from a genome have been arranged in an orderly fashion
68
gene flow
the movement of genes from one population to another
69
gene therapy
seeks to correct genetic disorders through genetic engineering and other methods that can alter gene function
70
genetic drift
a random process that can cause the gene pool of a population to change randomly from one generation to the next over time
71
natural selection
is a nonrandom, directional process that shifts the genetic characteristics of a population in one direction that leads to adaptation over successive generations
72
sexual dimorphism
males and females are distinctly different in appearance
73
sexual selection
when individuals differ in inherited characteristics that affect their ability to get mates
74
stem cell
undifferentiated cells with the extraordinary attribute of self renewal
75
zygote
union of an egg and sperm
76
adaptation
evolutionary process by which a population as a whole becomes better suited to its habitat
77
artificial selection
the breeding of animals and plants with specific, desirable characteristics
78
founder effect
occurs when a small group of individuals establishes a new population far from existing population
79
disruptive selection
changes in population genetics in which extreme values for a trait are favored over intermediate values
80
stabilizing selection
favor of the intermediate phenotypic traits

BIO 125 Struct. of Living Organisms (3 decks)

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