Glossary 1-11 Flashcards

1
Q

gene

A

the fundamental physical and functional unit of heredity, which carries information from one generation to the next; a segment of DNA.

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2
Q

genotype

A

the specific allelic constitution of an organism, either of the entire organism or for a certain set of genes or a certain gene.

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3
Q

phenotype

A

the morphological, biochemical and behavioural properties of an organism resulting from a specific genotype and its interaction with the environment.

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4
Q

genome

A

The genetic complement in a set of chromosomes

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5
Q

epigenetics

A

Changes in gene expression without changes in DNA sequence

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6
Q

telomere

A

The ends of a eukaryotic chromosome

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7
Q

semi-conservative replication of DNA

A

the method of DNA replication where the new molecule of DNA has one strand which comes from the parent molecule and one strand which is newly synthesised.

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8
Q

complementary base pairing

A

nucleotides or nucleotide sequences that are able to base pair. For example, G and C are complementary as are A and T.

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9
Q

pyrimidine

A

one of the two types of nitrogenous base compounds found in nucleotides. The pyrimidine bases in DNA are cytosine and thymine

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10
Q

purine

A

one of the two types of nitrogenous base compounds found in nucleotides. The purine bases in DNA are guanine and adenine.

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11
Q

polynucleotide

A

polymer consisting of nucleotide subunits.

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12
Q

phosphodiester bond

A

the chemical bond that links the adjacent nucleotides in a polynucleotide.

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13
Q

5’ (PO4) end

A

the end of the polynucleotide that terminates with a phosphate attached to the 5’- carbon of the sugar.

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14
Q

3’ (OH) end

A

the end of a polynucleotide which terminates with a hydroxyl group attached to the 3’- carbon of the sugar.

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15
Q

leading/ lagging strand

A

the leading strand is that which is synthesized continuously, whereas the lagging strand is synthesized in a discontinuous fashion during DNA replication.

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16
Q

Okazaki fragment

A

one of the RNA-primed short segments of DNA synthesized during replication of the lagging strand of the double helix.

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17
Q

DNA heliase

A

an enzyme that uses energy from ATP to unwind the DNA

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18
Q

topoisomerase

gyrase

A

an enzyme which can relax DNA by cutting and reforming the polynucleotide backbones

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19
Q

single-strand binding protein

A

one of the proteins that attaches to single stranded regions of DNA and prevents the reformation of base pairs, particularly in the region of the replication fork.

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20
Q

primase

A

an enzyme which synthesises the RNA primer

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21
Q

DNA polymerase I

A

enzyme which adds nucleotides to gaps when primers removed

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22
Q

DNA polymerase III

A

main polymerase which adds nucleotdes to template in a complementary way

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23
Q

ligase

A

enzyme which joins sequences of DNA

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24
Q

mutation

A

a change in the genetic material which can be passed from cell to cell or parent to offspring. A somatic mutation will occur in a somatic cell and hence will not passed to the next generation, compared to a germline mutation which can be passed to offspring.

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25
locus
the position of a gene on a chromosome
26
haploid
one copy of each chromosome
27
diploid
two of each type of chromosome the two similar chromosomes are described as homologous
28
aneuploidy
addition or deletion of a single chromosome or sometimes extra single chromosomes
29
euploidy
+/- a complete haploid set/s of chromosomes
30
autosome
a chromosome not involved in determining the sex of the organism
31
sex chromosome
a chromosome involved in determining the sex of the organism
32
dominant phenotype
the phenotype expressed in the heterozygote
33
recessive phenotype
the phenotype not expressed in the heterozygote
34
monohybrid cross
a crossing involving one gene where one parent is homozygous recessive, the other homozygous dominant, the F1 is heterozygous and the F2 is in a ratio 1:2:1 or 3:1
35
complete dominance
the homozygous dominant and the heterozygote have the same phenotype
36
codominance
the effect of each allele can be seen in the heterozygote eg., sickle cell anaemia
37
incomplete dominance
The heterozygote is a blended phenotype eg., flower colour
38
prototroph
With reference to bacteria/fungi an organism that can grow and divide on a substrate of minimal medium which contains inorganic salts, a carbon source for energy and water
39
auxotroph
A mutant organism (as above) which requires a compound to be added to minimal media to grow and divide.
40
pleiotropy
a single mutation which simultaneously affects several apparently unrelated aspects of the phenotype
41
phenocopy
a phenotype that results from and environmental factor that mimics a genetically caused phenotype mutation
42
lethal allele, lethal genotype, lethal mutation
an allele, genotype or mutation which results in death (may be lethal at different stages of development)
43
recessive lethal
results in death only in the homozygous state
44
dominant lethal
results in death when heterozygous or homozygous
45
hemizygous
A sex linked trait where only one copy of the allele is present eg., X linked trait in humans male is hemizygous, or Z linked trait in birds female is hemizygous
46
heterogametic
Produces two different types of gametes with respect to sex chromosomes
47
homogametic
Produces one type of gamete with respect to the sex chromosomes
48
pseudoautosomal region
Homologous regions on the ends of the X and Y chromosome
49
heterogametic sex
the sex which has two types of sex chromosome
50
homogametic sex
the sex which has one type of sex chromosome
51
hemizygous
in XY or ZW genotype the description of the genotype cf., | homozyous/heterozygous
52
hermaphrodite
Having both an active male gonad and female gonad
53
mosaic
A mixture of phenotypes
54
Barr body
An inactivated X chromosome
55
sex influenced trait
Usually autosomal trait seen in both sexes but more commonly in one
56
sex limited trait
Usually autosomal trait only seen in one sex however can be transmitted by either sex
57
sex influenced trait
Usually autosomal trait seen in both sexes but more commonly in one
58
sex limited trait
Usually autosomal trait only seen in one sex however can be transmitted by either sex
59
Didhybrid cross
As for monohybrid but involving two gene
60
Test cross
A cross to a homozygous individual
61
Back cross
A cross back to a parent
62
recessive epistasis
interaction between two genes affecting the same phenotypic trait, where the homozygous recessive genotype at one locus masks the effect of the alleles at the other locus eg., coat colour in mice
63
dominant epistasis
interaction between two genes affecting the same phenotypic trait, where the allele for the dominant trait at one locus masks the effect of the alleles at the other locus. eg., colour in plants (green/yellow/white)
64
antiserum A
serum containing antibody A
65
agglutination
The association of blood cells resulting form the interaction of the antigen on the surface of the red blood cell and the corresPponding antibody
66
non recombinant offspring (parental)
offspring resulting from a gamete in which with the same allelic arrangement of the parent is seen
67
recombinant offspring
offspring resulting from a gamete in which there has been crossing over and recombination between the loci being studied.
68
three point test cross
a cross involving three markers (gene loci) on a chromosome
69
single recombinant
gametes & offspring resulting from a cross in one region of a three point test cross
70
double recombinant
gametes & offspring resulting from a cross over in both regions of a three point test cross