Exam 1-Chs 2-7 Flashcards
(105 cards)
1
Q
Homologous pair
A
- A pair of chromosomes that are alike in structure and size
- Carry genetic info for the same set of hereditary characteristics
- 1 Chromosome of a homologous pair is inherited from male parent, 1 from female parent
2
Q
Diploid
A
-Possessing 2 sets of chromosomes (2 genomes)
3
Q
Haploid
A
-Possessing a single set of chromosomes (1 genome)
4
Q
Polyploid
A
-Possession of more than 2 sets of chromosomes
5
Q
Centromere
A
- Constricted region on a chromosome that stains less strongly than rest of chromosome
- Serves as attachment point for spindle microtubules
6
Q
Telomeres
A
-Stable end of a euaryotic chromosome
7
Q
Sister Chromatids
A
- Two copies of a chromosome that are held together at the centromere
- Each chromatid consists of a single DNA molecule
8
Q
Cell cycle
A
-Stages through which a cell passes through from one cell division to the next
9
Q
Checkpoints
A
-A key transition point at which progression to the next stage in the cell cycle is regulated
10
Q
Interphase
A
- Major phase of cell cycle btwn cell divisions
- Cell grows, develops, and prepares for cell division
11
Q
M (mitotic) phase
A
- Major phase of cell cycle that encompases active cell divisions
- Includes mitosis (nuclear division) and cytokinesis (cytoplasmic division)
12
Q
Mitosis
A
-Process by which the nucleus of a eukaryotic cell divides
13
Q
Cytokinesis
A
-Process by which the cytoplasm of a cell divides
14
Q
Prophase
A
- Stage of mitosis in which:
1. Chromosomes contract and become visible
2. Cytoskeleton breaks down
3. Mitotic spindles begin to form
15
Q
Condensins
A
- A group of proteins that bind to chromosomes as a cell enters prophase, causing the chromosome to become more compact and visible under a light microscope
16
Q
Prometaphase
A
- Stage of mitosis
- Nuclear membrane breaks down
- Spindle mictrotubules attach to chromosomes
17
Q
Metaphase
A
- Stage of mitosis
- Chromosomes aligh in middle of cell (metaphase plate)
18
Q
Anaphase
A
- Stage of mitosis
- chromatids separate and move toward spindle poles
19
Q
Telophase
A
- Stage of mitosis
- chromosomes arrive at the spindle poles
- Nuclear membrane reforms
- Chromosomes relax and lengthen
20
Q
Meiosis
A
- Process by which the chromosomes of a eukaryotic cell divide to give rise to haploid reproductive cells
- Meiosis 1 and 2
21
Q
Fertilization
A
-Fusion of gametes (sex cells) to form zygote
22
Q
Prophase I
A
- Stage in meiosis 1
- Chromosomes condense and pair
- Crossing over takes place
- Nuclear membrane breaks down
- Mitotic spindles form
23
Q
Synapsis
A
-Close pairing of homologous chromosomes
24
Q
Crossing Over
A
-Exchange of genetic material btwn homologous chromosomes but nonsister chromatids
25
Metaphase I
- Stage of meiosis I
| - Homologous pairs of chromosomes align at metaphase plate (center of cell)
26
Anaphase I
- Stage of meiosis I
| - Homologous chromosomes separate and move towards spindle poles
27
Telophase I
- Stage of meiosis I
| - Chromosomes arrive at spindle poles
28
Interkinesis
-Between meiosis I and II
29
Prophase II
- Stage of meiosis after interkenesis
- Chromosomes condense
- Nuclear membrane breaks down
- Spindles form
* *Some cells skip this stage
30
Metaphase II
- Stage of meiosis II
| - Individual chromosomes align in the center of the cell
31
Anaphase II
- Stage of meiosis II
| - Chromatids sepearate and move towards spindle poles
32
Telophase II
- Stage of meiosis II
| - Chromosomes arrive at spindle poles
33
Recombination
-Process that produces new combinations of alleles of a chromatid
34
Cohesin
- Molecule that holds the two sister chromatids of a chromosome together
- Breakdown at centromeres enables chromatids to separate in anaphase of mitosis and anaphase II
35
Genotype
-Set of alleles possessed by an individual organism
36
Homozygous
-Having two identical alleles at a locus
37
Heterozygous
-Having 2 non-identical alleles at a locus
38
Phenotype
-Appearance or manifestation of a characteristic
39
Monohybrid crosses
- A cross btwn individuals that are homozygous for diff alleles at same locus
- Also refers to cross btwn two individuals that are heterozygous for 2 alleles at single locus
* Differ in one characteristic
40
P (Parental) Generation
-1st set of parents in a genetic cross
41
F1 (First filial) Generation
-Offspring of the initial parents (P) in a genetic cross
42
Reciprocal crosses
- Pair of crosses in which the phenotype of the male and female parents are reversed
- Ex: cross w/ tall male and short female, another cross with short male and tall female
43
F2 (2nd filial) generation
- Offspring of F1 gen. in a genetic cross
| - 3rd gen. of genetic cross
44
Principle of segregation
- Principle of heredity discovered by Mendel
- Each diploid individual possesses 2 alleles at locus
- 2 alleles separate when gametes are formed, one allele goes to each gamete
45
Back cross
-Crosses btwn 1 F1 individual and 1 P individual
46
Probability
- Liklihood of the occurence of a particular event
- # of times a particular event occurs/ # of possible outcomes
- Ranges 0-1
47
Multiplication Rule
-Rule stating that the probability of 2 or more independent events occuring together is calculated by multiplying the probability of each of the individual events
48
Addition rule
-Ruel stating the probability of any 2 or more mutually exclusive events occuring is calculated by adding probabilities of the individual events
49
Conditional Probability
-Probability that is modified by additional info that another event has occured
50
Testcross
-Cross btwn an individual w/ an unknown genotype and an individual w/ the homozygous recessive genotype
51
Wild type
-The trait or allele that is most commonly found in natural populations
52
Dihybrid crosses
- Crosses btwn 2 individuals that differ in 2 characteristics
- Ex: cross btwn individuals that are homozygous for diff alleles at 2 loci OR cross btwn 2 individuals that are heterozygous at 2 loci
53
Principles of Independent Assortment
- Principle of heredity discovered by Mendel
- Genes encoding diff characteristics (genes at diff loci) separate independently
- Applies only to genes located on diff chromosomes or genes far apart on same chromosome
54
Chi^2
x^2= sum [(observed-expected)^2/expected]
Independent assortment: DF= n-1
Crossover-
--Df= (# of rows-1)x (#of columns-1)
-Expected= (row totalx column total)/ grand total
55
Hemizygous
- Possession of a single allele at a locus
| - Males of X-X/X-Y determination are hemizygous for x-linked loci bcuz only have 1 X chromosome
56
Nondisjunction
-Failure of homologous chromosomes or sister chromatids to separate in meiosis or mitosis
57
Dosage Compensation
- Equalization in males and females of the amount of protein produced by X-linked genes
- In placental mammals, accomplished by random inactivation of one x-chromsome in cells of females
58
Barr bodies
-Inactive X chromosome that appears as a condensed, darkly stained structure in most cells of female placental mammals
59
Pedigree
-Pictorial representation of a family history outlining the inheritance of one or more traits or diseases
60
Proband
-A person having a trait or disease who a pedigree is constructed
61
Consanguinity
-Mating btwn relatives
62
Genetic mosaics
-Condition in which regions of tissue w/in single individual have diff chromosome constitutions
63
Complete Dominance
- Type of dominance
- Same phenotype is expressed in homozygous and heterozygotes
- Only dom allele is expressed
64
Incomplete dominance
- Type of dom
| - Phenotype of heterozygote is intermediate btwn phenotype of 2 homozygotes
65
Codominance
-Type of allelic interaxction in which the heterozygote simultaneously expresses traits of both homozygotes
66
Incomplete penetrance
-A case in which some individuals possess the genotype for a trait but do not express the expected phenotype
67
Penetrance
-% of individuals w a particular genotype that express the phenotype expected of that genotype
68
Lethal Allele
- Allele that causes death of an individual organism
- Early in development
- Organism does not appear in progeny of genetic cross
- Recessive lethal allele kills homozygous recessive, dom lethal allele kills heterozygotes and homozygotes
69
Compound Heterozygote
-An individual w/ two diff recessive alleles at locus that result in a recessive phenotype
70
Gene Interaction
-Interaction btwn genes at diff loci that affect the same characteristics
71
Epistasis
-Type of gene in which gene at one locus masks or supresses the effects of a gene at a diff locus
72
Epistatic gene
-Genes that mask or supress the effect of a gene at diff locus
73
Hypostatic gene
-Gene that is masked by the action of a gene at a diff locus
74
Complementation test
- Test designed to determine whether 2 diff mutations at the same locus (allelic) or a diff locus (nonallelic)
- Two individuals who are homozygous for 2 diff mutations are crossed, producing F1 progeny that are heterozygous for the mutation
- If mutation at same locus= f1 mutant phenotype
- If at same locus= wildtype
75
Complementation
-Manifestation of 2 diff mutations in the heterozygous conditions as the wild-type phenotype; indicates that the mutations are at diff loci
76
Sex-influenced characteristics
- Characteristics encoded by autosomal genes that are more radically expressed in one sex
- Ex: autosomal dom gene may have higher penetrance in males than females, or gene is dom in males and recessive in females
77
Sex-limited characteristics
- Characteristics encoded by autosomal genes and expressed in only 1 sex
- Both males and females carry genes for sex-limited characteristics, but the characteristics appear in only one of the sexes
78
Cytoplasmic inheritance
- Inheritance of characteristics encoded by genes located in cytoplasm
- Most cytoplasmically inherited characteristics are inherited from 1 parent bcuz usually contributed by 1 parent
- Usually inherited from mother
79
Genetic maternal effect
-determination of the phenotype of an offspring not by its own genotype, but the nuclear genotype of its mother
80
genomic imprinting
-Differential expression of a gene that depends on the sex of the parent that transmitted the gene
81
Epigenetics
- Phenomena due to alterations in dna that do not include changes in the base sequence
- Often affect the way in which dna sequences are expressed
- Such alterations are often stable and heritable in the sense that they are passed to decendant cells or individuals
82
Temp-sensitive allele
-Allele that is expressed only at certain temps
83
Phenocopy
-Phenotype produced by environmental effects that is the same as the phenotype produced by a genotype
84
Discontinous characteristics
- Characteristics that exhibit only a few, easily distinguished phenotypes
- Ex: seeds being either round or wrinkled
85
Continuous characteristics
- Characterisitics that display large # of possible phenoytypes that are not easily distinguished
- Ex: human height
* or is encoded 4 multiple genetic factors
* Quantitative characteristics
86
Polygenetic characteristics
- Characteristics encoded by genes at many loci
| - aka mutliple genes 4 one characteristic
87
Pleiotropy
-Single gene influences multiple genes/phenotypes
88
Multifactorial Characteristics
-Characteristic determined by multiple genes and environmental factors
89
Recombination frequency
-Portion of recombinant progeny produced in a cross
| = # of recombo progeny/total # of progeny
90
Coupling
- Arrangement of linked genes
- wild type alleles of two or more genes are on one chromosome and their mutant alleles are on the homologous chromosome
- Also known as cis-configursation
91
Repulsion/trans configuration
- Arrangenment of 2 linked genes
| - each of a homologous pair of chromosomes contain one wild type (dominant) and one mutant (recessive) allele
92
Genetic Map
- Map of relative distances btwn genetic loci, markers, or other chromosome regions
- Determined by rates of recombination
- Measured on recombination frequencies or map units
93
Physical maps
- Map of physical distances btwn loci, genetic markers, or other chromosome segments
- Measured in base pairs
94
Two-point testcross
-Cross btwn an individual heterozygous at 2 loci and an individual homozygous for recessive alleles at those loci
95
Three-point testcross
-cross btwn an individual heterozygous at 3 loci and an individual homozygous for recessive alleles at 3 loci
96
Interference
-Degree to which one crossover interferes w/ additional crossovers
97
Coefficient of coincidence
observed double crossovers/ # expected doubel crossovers
98
Haplotype
-A specific set of linked genetic variants or alleles on a single chromosome or on part of a chromosome
99
Kinetochore
- Multiprotein comlex that assembles the centromere b4 cell division
- Spindle microtubules attach to it
100
Xist
-Activity of gene leads to a barr body being created
101
Allelic Series
-Multiple alleles at single gene that show a rank in order in their dominance relationships
102
Gene's w/ recombination of 50% or greater
- Tends to underestimate the true physical distance btwn them
- Doesn't take into account double crossovers that might take place--> restores original parental combo of alleles
103
Pangenesis
-Genetic information travels from different parts of the body to reproductive organs
104
Preformationism
-Minature organism resides in sex cell, all traits inherited from one parent
105
Blending inheritance
-Genes blend and mix
