Castle Williamson Flashcards
1
Q
genetics
A
study of genes, heredity and genetic variation in living organisms. it is generally considered a field of biology but overlaps many life sciences and is strongly linked with the study of informations systems
2
Q
molecular genetics
A
studies structure and function of genes at a molecular level. study of chromosomes and gene expression of an organism can give insight into hereditary, genetic variation, epigenetics and mutation
3
Q
luxturna
A
genetically modified virus that ferries a healthy gene into the eyes of patients with retinal dystrophy– first gene therapy for inherited diseases
4
Q
Genome
A
a complete set of genetic instructions for any organism
5
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transmission genetics
A
classical genetics, how traits are passed from one generation to the next
6
Q
molecular genetics
A
gene structure, function, and regulation
7
Q
population genetics
A
the study of genetic composition of groups (populations) and how gene frequency changes geographically or with time– essentially the study of evolution. also the analysis of patterns, causes and effects of health and disease conditions in defined populations
8
Q
model genetic organsims
A
organisms with charcteristics that make them useful for genetic analysis
- fruit fly, E. coli, C. elegans, yeast, zebrafish
9
Q
characteristics of model organisms
A
-short generation time
production of numerous progeny
-ability to carry out controlled genetics crosses
-ability to be reared in lab environment
-availability of numerous genetic variants
-accumulated body of knowledge about their genetics systems
*animal models are only valuable because of the basic similarity among all living things
10
Q
C. elegans
A
first multicellular organism to have its whole genome sequenced
11
Q
What are some of the implications of all organisms having similar genetic systems?
A
- that all life forms are genetically related
- research findings on one organisms gene function can often be applied to other organisms
- genes from one organism can often exist and thrive in another organsims
12
Q
Lamarckianism
A
if an adult organism changes during life in order to adapt to its environment, those changes are passed on to its offspring
13
Q
pangenesis
A
that that information needed to specify body parts traveled to the reproductive organs in packets (gemmules) which were packaged into sperm or eggs. the packets were then distributed as needed in the resulting embryo
14
Q
Theory of germ plasm
A
multicellular organisms organisms produce germ cells that contain and transmit heritable info, and somatic cells which carry out ordinary bodily functions and do not provide hereditary info
15
Q
gene
A
a distinct sequence of nucleotides forming part of a chromosome, a unit of hereditary that is transferred from parent to offspring
16
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allele
A
one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome
17
Q
chromosome
A
a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carry genetic info in the form of genes
18
Q
Prokaryotic cells
A
nucleus- Absent cell diameter- small 1-10 micrometer genome-once circular DNA molecule amount of DNA- relatively small membrane-cound organelles- absent
19
Q
eukaryotic cells
A
nucleus- present cell diameter- relatively large 10-100 micrometers genome- multiple linear DNA molecules DNA- complexed with histones Amount of DNA- relatively large membrane-bound organelles- present
20
Q
viruses
A
neither prokaryotic nor eukaryotic
outer protein coat surrounding nucleic acid
21
Q
homologous chromosomes
A
similar but not identical. each homolog carries the same genes in the same order, but the alleles for each trait may not be the same
22
Q
diploid cells
A
carry two sets of genetic information
23
Q
haploid cells
A
carry one set of genetic info– gametes
24
Q
centromere
A
attachment point for spindle microtubules
25
telomeres
tips of linear chromosomes-- gradually shorten over lifetime
26
origin of replication
where the DNA synthesis starts
27
submetacentric
centromere situated so that one chromosome arm is somewhat shorter than the other
28
metacentric
centromere in the middle
29
telocentric
centromere at the end with no short arm visible in a light microscope
30
acrocentric
centromere near the end producing a short arm
31
interphase
an extended period between divisions, DNA synthesis, and chromosome replication phase
32
M phase
mitotic phase
33
Check points
key transition points
G1/s- check point - regulated decision point
G2/M- check point- only passed if DNA completely replicated and undamaged
34
mitosis
separation of sister chromatids
35
cytokinesis
separation of cytoplasm
36
prophase
chromosomes condense and mitotic spindle forms
37
prometaphase
nuclear envelope disintegrates and spindle microtubules anchor to kinetochores
38
metaphase
chromosomes align on the metaphase plate, spindle assembly check point
39
anaphase
sister chromatids separate becoming indivual chromosomes that migrate toward spindle poles
40
Telophase
chromosomes arrive at spindle poles, the nuclear envelope re-forms and the condensed chromosomes relax
41
What is the correct order of stages in the cell cycle
G1, S, prophase, metaphase, anaphase
42
meiosis
production of haploid gametes
43
fertilization
the fusion of haploid gametes
44
genetic variation
consequence of meiosis
45
meiosis 1
separation of homologous chromosome pairs and reduction of the chromosome number by half
46
meiosis 2
separation of sister chromatids also known as equational divison
47
meiosis 1 -- prophase 1
synapsis- close pairing of homologous chromosomes
tetrad- closely associated 4-sister chromatids of 2 homologous chromosomes
crossing over
48
crossing over
crossing over of chromosome segments from the sister chromatid of one one chromosome to the sister chromatid of the other synapsed chromosomes- exchange of genetic info the first mechanism that generates genetic variation in newly formed gametes
-can result in unequal exchange of genetic material producing chromosomes with deleted or duplicated regions
49
meiosis 1 -- metaphase 1
random alignment of homologous pairs of chromosomes along the metaphase plate
50
meiosis 1-- anaphase 1
separation of homologous chromosome pairs and the random distribution of chromosomes into 2 newly divided cells- second mechanism of generating genetic variation in formed gametes
51
which of the following events take place in meiosis 2 but not meiosis 1
separation of chromatids
52
cohesin
is a protein complex that holds the chromatids together and is key to the behavior of chromosomes in mitosis and meiosis
53
spermatogenesis
male gamete production
54
oogenesis
female gamete production
55
Klinefelter sydrome
XXY male y overrides x always
56
heredity
passing on of physical or mental characteristics genetically from one generation to another
57
heritability
the proportion of total variation between individuals in a given population that is due to genetic variation
58
pheomelanin
predominant pigment that results in red hair
59
monohybrid cross
cross between two parents that differ in a single characteristic
-3:1
60
homozygous
true breeding the alleles are identical
61
principle of segregation (Mendel's First Law)
ech individual diploid organism possesses two alleles for any particular characteristic and only one is passed to offspring
62
independent assortment
alleles segregate independently when gametes are formed
63
Concept of dominance
when 2 different alleles are present in a genotype only the trait encoded by one of them - the dominant allele- is observed in the phenotype. the other is recessive
64
multiplication rule
multiply the probability of independent events happening simultaneously
65
addition rule
when two events are mutually exclusive the probability that either A or B will occur is the sum of the probability of each event
66
conditional probability
the probability of an event A given that another B has already occurred
67
dihybrid cross
involves 2 traits with differing alleles
- easiest if they are dominant and recessive
- relate the principle of independent assortment to meiosis
- genes located on different chromosomes will sort independently
- 9:3:3:1
68
chi-square goodness of fit
a statistical test that indicates the probability that the difference between the observed and expected values is due to chance
assumptions:
- random sample- sample data is a random sample of a large population
- sample size- is sufficiently large to prevent small sample error
- independence- observations are independent of each other
69
degrees of freedom
number of values that are free to vary minus 1
70
how are the principles of segregation and independent assortment related and how are they different
- genes encoding different characteristics separate and assort independently of one another when they are not located close together on the same chromosome
- during this process two alleles of the same gene encoding one characteristic still have to be segregated from each other during the formation of gametes
71
multiple testing correction
refers to recalculating probabilities obtained from a statistical test which was repeated multiple times
- threshold to achieve significance is more difficult to achieve
72
heterogametic
produces 2 different gamete types - 2 different sex chromosomes
73
hermaphroditism
both sexes in the same organism mostly invertebrates
74
monoecious
both male and female reproductive structures in the same organism, plants
75
dioecious
either male or female reproductive structures but not both
76
how does the heterogametic sex differ from homogametic sex
gametes of heterogametic sex have different sex chromosomes, gametes of homogametic sex have the same sex chromosome
77
haplodiploidy system
haploid set- male
diploid set- female
bees
78
turner syndrome
XO female
79
dosage compensation
inactivation of 1 X chromosome to compensate for different X dosage between the sexes
80
Lyon hypothesis
named after Mary Lyon suggested that dosage compensation in mammals by inactivation of all but 1 X chromosome in cells with more than one X chromosome. theBarr body visible in some female mammalian cells is an inactivated X chromosome
81
Mosaicism
a condition in which cells with in the same person have different genetic makeup
when different X chromosomes are inactivated in neighboring cells
82
genetic linkage
the tendency of alleles that are located close together on a chromosome to be inherited together during meiosis. linked genes will segregate together and not obey mendels second law
83
linkage disequilibrium
the non-random association of alleles at different loci. Loci are said to be in linkage disequilibrium when the frequency of association of their different allele is higher or lower that what would be expected if the loci were segregating independently
84
non-mendelian inheritance
refers to any patter of inheritancein which traits do not segregate in accordance with Mendel's laws
85
complete dominance
phenotype of the heterozygote is the same as the phenotype of one of the homozygotes
86
incomplete dominance
phenotype of the heterozygote is intermediate (falls within the range) between the phenotypes of the two homozygotes
87
codominance
phenotype of the heterozygote includes the phenotypes of both homozygotes
88
penetrance
the percentage of individuals having a particular genotype that express the expected phenotype
89
expressivity
the degree to which a character is expressed
90
complete penetrance
everyone who inherits the disease causing alleles has some symptoms
91
incomplete penetrance
some individuals do not express the phenotype even though they inherit the alleles ex: polydactyly
92
variable expression
symptoms vary in intensity in different people
| ex: two extra digits vs three
93
lethal allele
causes death at an early stage of development and so some genotypes may not appear among progeny
94
gene interaction
effects of genes at one locus depend on the presence of genes at other loci
- gene interaction can produce novel phenotype
- gene interaction with epistasis: one gene masks the effect of another
95
epistasis
one gene masks or influences the effect of another gene
| ex: coat color in dogs
96
recessive epistasis
recessive alleles at one locus mask the mask the phenotypic locus of other gene locus
ex: bombay blood type-- no H antigen made
97
dominant epistasis
when the dominant allele masks the expression of all alleles of another gene
ex: summer squash need two enzymes to get yellow color if you only have one you get green but if you have a dominant W allele it blocks the whole cascade and you get a white squash
98
duplicate recessive epistasis
9:7 ratio when recessive alleles at either two loci can mask the expression of dominant alleles at the two loci
A.K.A complementary epistasis
ex: snails - to get a brown snail you have to have 2 enzymes so at least one dominant allele is needed at each locus to get brown snails. if either locus is homozygous recessive you get white snail
99
pleiotropy
one gene is able to affect multiple phenotypic characters
100
complementation
occurs when two strains of an organism with different homozygous recessive mutations that produce the same mutant phenotype produce offspring with the wild type phenotype when mated or crossed
ex: change in wing structure in flies
101
sex- influenced traits
are controlled by genes present on autosomes hence such genes are present in both sexes but their expression is different in males vs. females usually because the expression responds differently to androgens and estrogens
Ex: soft vs coarse facial hair, male pattern baldness
phenotype determined by: autosomal genes that are more readily expressed in one sex
102
sex-limited characteristics
characteristics are inherited according to mendel's principles
-precocious puberty
phenotype determined by: autosomal genes whose expression is limited to one sex
103
genomic imprinting
differential expression of genetic material depending on whether it is inherited from the male or female parent
104
epigenetics
phenomena due to alterations to DNA that do not include changes in the base sequence often affect the way in which the DNA sequences are expressed
105
IGF2
protein hormone involved in the regulation of cell proliferation, growth, migration, differentiation, and survival. preferentially expressed in early embryonic and fetal development and in a wide variety of somatic tissues. exclusively from paternal allele
106
anticipation
a genetic trait becomes more strongly expressed or is expressed at an earlier state as it is passed from generation to generation
-occurs due to expansion of an unstable region of DNA from generation to generation
Ex- fragile X, Huntingtons, friedreich ataxia, myotonic dystrophy
107
Fragile X
genetic disorder which occurs as a result of a mutation of the fragile X mental retardation 1 (FMR1) gene on the X chromosome, most commonly an increase in the number of CGG trinucleotide repeats in the 5" untranslated region of FMR1. most common cause of inherited learning difficulties
108
temperature dependent sex determination
changes in temperature during embryogenesis change gene expression resulting resulting in a significant change in phenotype
109
temperature sensitive allele
an allele whose product is functional only above or below a threshold temperature
Ex: simese cats and himalayan rabbits
110
discontinuous characteristics
relatively few phenotypes
111
continuous characteristics
continuous distribution of phenotypes; occurs when genes at many loci interact
112
polygenic characteristics
characteristics encoded by genes at many loci
113
heterosis
A.K.A- hybrid vigor
is the improved or increased function of any biological quality in a hybrid offspring of pure bred strains
-opposite of inbreeding
-increase of heterozygosity improves such characteristics as size, growth rate, or yield of a hybrid organism over either of its parents
-ex: mule
114
adermatoglyphia
the absence of ridges on the skin on the pads of the fingers and toes
gene: SMARCAD1
115
pedigree chart
a document used by genealogist in study family history
116
pedigree
pictorial representations of a family hx, a family tree that outlines inheritance of one or more characteristics
117
proband
the person from whom the pedigree is initiated
118
common rule
requirements for assuring compliance by research institutions, requirements for researchers obtaining and documenting informed consent, requirements for IRB membership, function, operations, review of research, and record keeping, additional protection for certain vulnerable subjects- pregnant women, prisoners, and children
119
autosomal recessive traits
normally appear with equal frequency in both sexes and seem to skip generations
120
autosomal dominant traits
normally appear with equal frequency in both sexes and don't skip generations
Ex: familial hypercholesterolemia: very high levels of LDL
121
X-linked recessive traits
appear more often in males than in females and are not passed from father to son
Ex: Duschenne's MD, hemophilia
122
X-linked hypophosphatemia
ex: of X-linked dominant disorder
| form of rickets that differs bc ingestion of vitamin D doesn't really help
123
Y-linked traits
appear only in males and are passed from father to all of his sons
124
dizygotic twins
not identical
125
monozygotic twins
identical
126
concordant trait
a trait shared by both members of a twin pair
127
concordance
the percentage of twin pairs that are the same for a trait
128
chorionic villus sampling
- CVS can be performed early in pregnancy
- under US guidance a catheter is inserted through the vagina and cervix into the uterus
- placed into contact with the chorion, the outer layer of the placenta
- suction removes a small piece of chorion
- cells of chorion are used directly for many genetic tests and culturing is not required
129
Amniocentesis
- under US guidance a sterile needle is inserted through the abd wall into the amniotic sac
- a small amount of fluid is withdrawn through the needle
- the amniotic fluid contains fetal cells which are separated from the amniotic fluid
- cultured cells
- tests are performed on cultured cells
130
Recombination
alleles sort into new combinations
131
complete linkage
leads to nonrecombinant gametes and nonrecombinant progeny
132
crossing over
disrupts linked and leads to recombinant gametes and recombinant progeny
133
single crossover
half nonrecombinant gametes and half recombinant gametes
134
calculating recombination frequency
recombination= (No. recombinant progeny/total no. of progeny) x 100%
135
coupling (cis configuration)
one chromosome contains both wild type alleles, one chomosome contains both mutant alleles
136
repulsion (trans configuration)
wild-type allele and mutant allele are found on the same chromosome
137
genetic maps
are determined by recombinant frequency
| map unit or centimorgan= crossover frequency of .01 in a single generation
138
physical maps
are determined by nucleotide position
139
coefficient of coincidence
number of observed double crossovers/number of expected double crossovers
140
interference
1- coefficient of coincidence
141
two-stand double cross over
0% detectable recombinants
142
three-strand double cross over
50% detectable recombinants
143
four-strand double cross over
100% detectable recombinants
| 50% average detectable recombinants
144
nail-patella syndrome
autosomal dominant- poorly developed nails and patellas, linkage between ABO blood types
145
haplotype
a set of DNA variations or polymorphisms that tend to be inherited together
146
genomic wide association studies (GWAS)
examine genetic sequence variants across the entire genome to find those that are associated with a trait or disease
147
karyotyping
chromosomes prepared form actively dividing cells, halted in metaphase with colchicine, chromosomes arranged according to size
148
Banding
G bands: giemsa stain, heterochromatin stains dark euchromatin stains light
Q bands: quinacrine stain, AT rich regions
C bands: reveals centromeric heterochromatin
R bands: regions rich in C-G base pairs
T bands: telomeric banding after heat denaturation
149
aneuploidy
loss or gain of chromosomes
| causes: deletion of centromere during mitosis, robertsonian translocation, nondisjunction during meiosis and mitosis
150
polyploidy
those containing more than two complete paired homologous sets of chromosomes
151
deletion
loss of chromosomal segments
| effects: imbalances in gene products, expression of normally recessive gene (pseudodominance), haplosufficiency
152
paracentric inversion
an inversion in which the breakpoints are confined to one arm of a chromosome, the inverted segment does not span the centromere
153
pericentric inversion
an inversion in which the breakpoints occur on both arms of a chromosome, the inverted segment spans the centromere
154
robertsonian translocation
rare chromosomal rearrangements that in humans generally occur in the five acrocentric chromosomes 13, 14, 15, 21, 22
155
reciprocal translocation
an exchange of material between two nonhomologous chromosomes
156
nonreciprocal translocation
transfer of genes from one chromosome to another nonhomologous chromosome
157
Dicentric
a fragment results without a centromere and the other had 2 centromeres
results in nonfxn'l gametes
158
nullisomy
loss of both members of a homologous pair of chromosomes
| 2n-2
159
monosomy
loss of a single chromosome
| 2n-1
160
trisomy
gain of a single chromosome
| 2n+1
161
tetrasomy
gain of two homologous chromosomes
| 2n+2
162
autopolyploidy
from a single species
163
allopolyploidy
from 2 or more species
164
medical cytogenetics
part of clinical medicine that studies a relationship between chromosomal alterations and genetic diseases in humans
165
fluorescence in situ hybridization (FISH)
technique in which DNA probe containing 1 or more genes is labeled with fluorescent dye and then hybridized to interphase or metaphase cells, used to detect small regions of deletions or duplications, used to examine specific regions of the genome in non-dividing tissues, used to map genes
166
constitutional cytogenetic abnormality
homogenous abnormality- anomaly in oocyte formation
| mosaic abnormality- anomaly in zygote formation
167
acquired chromosomal
anomaly in somatic cells
