Before midterm Flashcards
(248 cards)
1
Q
DNA
A
Deoxyribonucleic acid; information-carrying genetic material that compromises the genes
2
Q
RNA
A
Ribonucleic acid; information-carrying material derived from DNA by transcription
3
Q
Polymers
A
Subunits bonded together
4
Q
Nucleotide
A
Polymer of DNA and RNA compromised of:
Phosphate group
5-C sugar
Cyclic N-containing base
5
Q
Adenine
A
Purine base found in RNA and DNA
6
Q
Thymine
A
Pyrimidine base found in DNA
7
Q
Cytosine
A
Pyrimidine base found in DNA and RNA
8
Q
Guanine
A
Purine base found in DNA and RNA
9
Q
Uracil
A
Pyrimidine base found in RNA in place of thymine
10
Q
Pairs with thymine
A
Adenine
11
Q
Pairs with cytosine
A
Guanine
12
Q
Purine
A
Double-ring bases
i.e. Adenine and Guanine
13
Q
Pyrimidine
A
Single-ring bases
i.e. Cytosine and thymine
14
Q
Phosphodiester bonds
A
Connect nucleotides
15
Q
Characteristics of DNA structure
A
Double-helix
Two strands held together by hydrogen bonds between complementary bases
Strands run antiparallel
Two strands have opposite chemical polarity
16
Q
Makes DNA uniquely suited to store and transmit genetic information
A
Complementarity of strands
17
Q
Two strands have opposite chemical polarity
A
One runs 5’ to 3’ so at the 5’ end there is a free phosphate group and at the other a free hydroxyl group
The other strand runs 3’ to 5’
18
Q
Most common form of DNA
A
B-DNA (conformation that DNA takes under physiological conditions (aqueous protoplasms)
19
Q
Important for protein binding
A
Major and minor grooves
20
Q
Major and minor grooves
A
Two grooves of a DNA double helix are not identical
21
Q
Chromatin
A
Complex of DNA and proteins in eukaryotic chromosomes
22
Q
Chromosome
A
Darkly staining nucleoprotein bodies that are observed in cells during division. Each chromosome carries a linear array of genes
23
Q
How do we go from DNA to chromosome?
A
Chromosomes contain a single giant molecule of DNA extending from one end to the other but is highly condensed (needs to be in order to get 3 billion genes into one tiny cell)
24
Q
Chromosomes are composed of
A
DNA, RNA, proteins
25
First level of condensation
Packaging DNA as negative supercoil into nucleosomes (2nm --> 11nm)
26
Produces an 11 nm fibre
First level of condensation (negative surer coil)
27
Nucleosome
Nuclease-resistant subunit of chromatin that consists of about 146 nucleotides of DNA wrapped around 8 histone proteins
28
Nucleosome core
8 histone protein core (octamer) chills while being wrapped in DNA
29
Linker region
Space connecting nucleosome balls
| Bunch of DNA that varies in length from 8 to 114 nucleotide pairs
30
Endonuclease
Enzymes inside nucleus
31
Second level of condensation
Additional folding or supercoiling of 11 nm nucleosome fibre to produce a 30 nm chromatin fibre
Driven by nucleosomal interactions and histone H1 very improtant
32
30 nm fibre
The basic structural unit of the metaphase chromosome (DNA in its most condensed form
33
Histones
Group of proteins rich in basic amino acids that function in the coiling of DNA in chromosomes and in the regulation of gene activity
34
H1
After DNA wraps around nucleosome core, 9th guy (histone) comes in and anchors to seal the deal forming a complete nucleosome
35
Complete nucleosome
DNA wrapped around 8 histone protein core and then anchored by 9th histone called Histone H1
36
Third level of condensation
Attachment of the 30 nm fibre at many positions to a non-histone protein scaffold
37
Cohesins
Proteins that hold sister chromatids together at centromere
38
Condensins
Proteins that function to condense 30 nm DNA fiber of chromatin within one sister chromatid
39
Non-histone units
Cohesin and condensins
40
Centromere
Provide the point of attachment of chromosomes to microtubules in the mitotic spindle
41
Important for meiotic and mitotic processes
Centromeres
42
Mitotic spindle
Macromolecular machine that segregates chromosomes to two daughter cells during mitosis
43
Telomeres
These guys chill on the ends of chromosome to protect them from being eaten by enzymes and to prevent them for merging together with other chromosome ends and facilitate replication of the ends of the linear DNA
44
Mitosis
Disjunction of duplicated chromosomes and division of the cytoplasm to produce two genetically identical daughter cells
45
Diploid
An organism or cell with two sets of chromosomes (2n) or two genomes
46
Haploid
An organism or cell having only one complete set of chromosomes (n) or one genome
47
Two diploid cells
Final product of mitosis of diploid cell
48
Four haploid cells
Final product of meiosis of diploid cell
49
Chromatid
One of the two identical strands resulting from self-duplication of a chromosome in mitosis or meiosis
50
Identical sister chromatids
Each mitotic chromosome is comprised of a pair of sister chromatids (so real name of chromosomes)
51
Daughter cell
Product of cell division
52
Disjunction
Separation of homologous chromosomes during anaphase of mitotic or meiotic divisions
53
In mitosis ________ __________ and ___________ ________ are divided more or less equally between daughter cells
Cellular organelles, cytoplasmic contents
54
In mitosis __ and _____ _______ are fragmented at the time of division and reformed in the daughter cells
E.R., Golgi complex
55
___________ and ____________ are randomly divided between daughter cells
Mitochondria, chloroplasts
56
_______ ___________ must be duplicated exactly and distributed equally and exactly to daughter cells
Nuclear chromosomes
57
Cell Cycle
Set of stages of cell division
58
Main stages of cell cycle
```
G1
S
G2
M
Interphase
```
59
G1 phase
Gap 1: Growth, cellular metabolism
60
S phase
Synthesis: DNA replication (chromosome duplication)
61
G2 phase
Gap 2: Preparation for mitosis
62
M phase
Mitosis: Chromosomal separation and cytokinesis
63
Interphase
The time between successive mitoses
64
Cells that are not actively cycling
Enter a state called G0 from G1 and are said to be quiescent
65
Preparation for mitosis
Making proteins like cohesins and condensins
66
When mitosis begins
Each chromosome has been duplicated
67
"c"
DNA content
68
DNA content in haploid cell
"c"
69
DNA content in diploid cell
"2c"
70
Number of unique genes
"n"
71
Weight of DNA
"c"
72
Somatic cell
A cell that is a component of the body, in contrast with a germ cell that is capable, when fertilized, of reproducing the organism
73
Diploid somatic cell
"2n, 2c"
74
Diploid somatic cell after DNA replication
"2n, 4c"
75
IPMAT
```
Cycle of mitosis:
Interphase
Prophase
Metaphase
Anaphase
Telophase
```
76
Interphase
Chromosmes duplicate to produce sister chromatids
77
Homologous chromosomes
Chromosomes that occur in pairs and are generally similar in size and shape, one having come from the male parent and one from the female parent
78
Chromosomes containing the same array of genes
Homologous chromosomes
79
Prophase
Duplicated chromosomes condense, holding on through cohesin and condensin
80
Metaphase
Duplicated chromosomes migrate to the equatorial plane (midway between spindle poles) of the cell and the nuclear membrane breaks down
81
Anaphase
Cohesion breaks down and sister chromatids of each duplicated chromosome move to opposite poles of the cell, spindle poles moving further apart
82
Telophase
Chromosomes cluster at opposite spindle poles and become dispersed and decondense (condensin is degraded) finally a nuclear envelope assembles around chromosomes
83
Cytokinesis
During telophase daughter cells form and are "2n, 2c" once again
84
Microtubule organizing center (MTOCs)
Region in eukaryotic cell that generates microtubules used during cell division
Always exist but only organize during mitosis
85
Short arm
"p"
86
Long arm
"q"
87
Occurs in bodies stem cells
Mitosis
88
Occurs in germ (sex) cells
Meiosis
89
A cell that is about to divide
Parent cell
90
Daughter cells
Products of division
91
When meiosis begins
Duplicated gene
92
23 pairs of chromosomes
Somatic human cells
93
Different pairs of chromosomes
Carry different sets of genes
94
Homologues
Carry the same set of genes
95
Heterologues
Chromosomes from different pairs
96
Involves two cell divisions
Meiosis
97
Meiosis I
Homologous chromosomes separate
98
Meisosis II
Sister chromatids separate
99
Major difference in meiosis and mitosis
Prophase to metaphase
100
Prophase I
1. Leptonema
2. Zygonema
3. Pachynema
4. Diplonema
5. Diakensis
101
Leptonema
Chromosomes each consisting of two sister chromatids begin to condense
102
Zygonema
Homologous chromosomen begin to pair
103
Pachynema
Homologous chromosomes are fully paired, crossing over happens
104
Diplonema
Homologous chromosomes separate except at chiasmata
105
Crossing over
Breakage of chromatids and exchange of broken pieces between homologous chromosomes (non-sister chromatids)
106
Chiasmata
Following crossing over homologous chromosomes start to pull apart but remained joined at cross-over junctions
107
Synapsis
Pairing of homologous chromosomes
108
Reduction division
Cell division in meiosis I
109
Non-disjunction
Failure of two homologous chromosomes to pass to separate cells
110
Down-syndrome
Chromosome non-disjunction
111
Meiosis I produces
Two haploid daughter cells that are genetically distinct
112
Diakensis
Paired chromosomes condense further and become attached to spindle fibers
113
Metaphase I
Paired chromosomes align at the equatorial plane in the cell
114
Anaphase I
Homologous chromosomes disjoin and move to opposite poles of the cell
115
Telophase I
Chromosome movement is completed and new nuclei begin to form
116
Meiosis II
Resembles a mitotic division except the products are haploid
117
Spermatogenesis
The process by which maturation of the gametes of male takes place. All four develop into sperm
118
Oogenesis
The formation of the egg or ovum in animals. Usually only one of the four haploid cells becomes an egg the other three degenerate
119
Locus
Specific region on a chromosome (could be a gene or any unique sequence)
120
Allele
Alternate form of a gene (A or a)
121
Upper case letter
Dominant allele
122
Dominant allele
Expressed factor
123
Recessive allele
Latent factor
124
Lower case letter
Recessive allele
125
Alleles are typically designated after the
Recessive trait
126
Genotype
Allelic combination
127
Phenotype
Physical appearance
128
Wild type
The customary phenotype or standard for comparison
129
Gametogenesis
Formation of gametes beginning when undifferentiated diploid cells undergo meiosis to produce haploid cells. The haploid cells then differentiate into mature gametes "n, c"
130
Spermatogonia, oogonia
Undifferentiated diploid cells "2n, 2c"
131
Primary o/spermat-ocyte
Before completion of first meiotic division "2n. 4c"
132
Secondary o/spermat-ocyte
After completion of first meiotic division "n, 2c"
133
Gametes
Mature male or female reproductive cell
134
Inbreeding
Matings between related individuals
135
Inbreeding leads to
High probability of recessive mutations popping up
136
Designed to study one trait at a time
Mendel's experiments
137
Homozygous
Both alleles are identical (ll or aa or BB)
138
Heterozygous
Two alleles are different (Ll or aA or Bb)
139
P0
Parental generation in a genetic cross
140
F1
Offspring generation in a genetic cross
141
F2
Grand-offspring generation in a genetic cross
142
Monohybrid cross
A cross between parents in which only one trait is being considered
143
Mendel's heritable factor
Gene
144
Principle of dominance
In a heterozygote one allele may conceal the presence of another
145
Principle of segregation
In a heterozygote two different alleles (l and L) segregate from each other during the formation of gametes
146
Hybrid
An offspring of a cross between unrelated strains (homo parents different in one or more genes)
147
Principle of independent assortment
Alleles on different pairs of chromosomes assort independently from one another, occurring during anaphase 1 of the meiotic cycle
148
Monohybrid cross ratio
3:1
149
Dihybrid cross ratio
9:3:3:1
150
Produces one kind of gamete
Homozygous parent
151
Equation for possible haploid gametes?
Alleles^genes
152
Punnet square method
Possible gametes go across top and side then fill in square
153
Forked-line method
Look at each gene independent of one another
154
Probability method
Find probability of each independent event occurring
155
Multiplicative rule
Probability of independent events occurring together is the product of their individual probabilities of occurrence (and = X)
156
Additive rule
Probability of at least one event happening is the sum of their individual probabilities (or = +)
157
Test cross
Performed to determine individual's genotype. Individual of unknown genotype must be crossed with a homozygous recessive individual
158
Pedigrees
Diagrams that show the relationships among the members of a family
159
Trait is likely showing a recessive mode of inheritance
If...
the trait suddenly appears in a pedigree
the trait "skips" a generation
160
Assume that unrelated individuals marrying into the family...
Do not carry the recessive allele
161
A trait is likely showing a dominant mode of inheritance
If...
every individual has at least one affected parent
the trait is manifested in at least one individual in every generation once the trait appears
162
Binomial probability
```
For a total number of "n" progeny we can calculate that exactly "x" number will fall into one class and "y" number will fall into another
(n!/x!y!)p^xq^y
```
163
The absence of a phenotype
Doesn't necessarily reflect the absence of a causative genotype
164
Huntington's disease
Neurodegenerative disorder in humans caused by an autosomal dominant mutation and one of the first genetic diseases mapped on pedigree scheme
165
Autosomal chromosomes
Not a sex chromosome (22)
166
XX
Females
167
XY
Male
168
Pseudoautosomal genes
Genes present on both the X and Y chromosomes but mostly in the terminal regions. They do no follow X or Y-linked patterns of inheritance
169
Hemizygous
Only one copy of chromosome
| Gene on X chromosome doesn't have homolog on Y chromosome
170
X-linked mutation
In a hemizygous state (XY) if one gene is mutated and is recessive the recessive allele would manifest itself. In a heterozygous state the recessive allele would be suppressed by dominant wild type allele (XX)
171
X-linked recessive disorder
Hemophilia or colorblindness
172
More common in males than in females
Disorders which are caused by recessive X-linked mutations
173
Y chromsome
Carries fewer genes than the X chromosome
174
X-inactivation
Dosage compensation of X-linked genes (i.e. not fair that there are twice as many genes on the X chromosome in females than in males so in mammals one of the female X-chromosomes are inactivated)
175
Barr body
A condensed mass of chromatin found in the nuclei of placental mammals that contains one or more X chromosomes (altered state of inactive X-chromosome)
176
Dosage compensation in Drosophila
Achieved by hyper activating the single X chromosome in males
177
Dosage compensation in cats and mice
Results in a mosaic coat colour because the gene for coat colour resides on the X-chromsome
178
Mutation
A change in the DNA at a particular locus in an organism
179
Spontaneous mutations
A result of an error during DNA synthesis:
- Incorporation of rare isoforms of the four bases that have altered base pairing properties
- The inherent fallibility of replication proteins
180
Tautomers
Two existing isoforms of the nitrogenous bases of DNA
181
Incorporation of a rare isoform during DNA replication
Can lead to a change in DNA sequence
182
Rare isoforms
Have altered base pairing properties
183
Inherited mutations
Mutations of DNA in the germ line (during mitotic divisions of spermatogonia or oogonia)
184
Palindromes
A segment of DNA in which the base-pair sequence reads the same in both directions from a central point of symmetry
185
Hot spots for spontaneous mutations during DNA synthesis
Simple repeats
Symmetrical repeats
Palindromes
186
Induced mutations
Exposure to chemical mutagens
Exposure to radiation (UV light)
DNA transposable elements
187
Thymine dimer
Pyrimidines adsorb UV energy resulting in dimerization. This creates a hiccup for DNA polymerase and it causes changes in DNA sequence
188
Point mutation
Changes that occur at specific sites in genes (involving a change of only one nucleotide base)
189
Three types of point mutations
1. Silent
2. Nonsense
3. Missense
190
Silent mutation
When the one nucleotide base that is changed creates a codon synonymous to the original codon then the mutation has no effect
191
Nonsense mutation
When the one nucleotide base alters the codon so that it creates a premature stop codon
192
Missense mutation
When the one nucleotide base alters a codon so that it no longer makes sense (specifying a different amino acid than the original codon)
193
Frameshift mutations
A mutation that changes the reading frame of an mRNA (either by inserting or deleting nucleotides)
194
Types of frameshift mutation
1. Insertion
| 2. Deletion
195
Insertion mutation
When a series of extra base pairs is inserted into DNA
196
Deletion mutation
When a series of DNA base pairs are deleted or lost
197
Mutations that affect the coding region
1. Change protein to a non-functional form
- premature truncation
- changes to protein folding
2. Changes in post-translational modification
- prevent proper localization of the protein
- "unactivatable"
198
Changes to protein folding
- Prevent proper localization of the protein
- Targeted for degredation
- Compromised activity
199
Mutations that affect non-coding regions
1. Prevent or reduce transcription
2. Prevent or reduce translation
- mRNA is unstbale
- ribosomes can't bind
- mutation of the start codon
200
____________ _________ are mutations that occur without a known cause
Spontaneous mutations
201
Polymorphism
Ant allele found at appreciable frequencies (at least 1%) in the population
202
Different mutations in a gene
Can cause the same disorder
203
Almost always involve a loss of gene function
Recessive mutations
204
Null allele
Complete loss of function
205
Partial loss of function
hypomorphic allele
206
Dominant mutations
Can involve a loss of protein function OR a gain of protein function
207
Incomplete dominance
A loss of function mutation where mutant phenotype of Aa is between AA and Aa (heterozygotes with one copy of the dominant allele have half the functional gene dosage)
208
Dominant negative
A loss of function mutation that can interfere with function of the wild type protein
209
Gain of function mutation
- Enhances the function of the wild type protein
| - A new function is created
210
Antenna mutation in Drosophila
(Dominant) gan of function mutation
211
Codominance
Heterozygote expresses the phenotypes of both homozygotes
212
Allelic series
Describes the dominance hierarchy of multiple alleles
213
Outside Mendel's garden
- Genes may (and usually) have more than 2 alleles
- Different alleles may affect the phenotype in different ways
- A single gene may control several traits
- Multiple genes may control a single trait
214
Complementation test
You wan to find out if you have a new mutation in a novel gene, or is it just another allele of an already known mutation so you cross the two mutants together and whatever phenotype you get has to be explained by Mendelian ratios
215
Phenotypes are influence by
Both genetic and environmental factors
216
Conditional alleles/mutations
Expressivity is environmentally-dependent
217
Incomplete penetrance
Individuals do not express a trait even though they have the appropriate genotype
218
Variable expressivity
A trait is not manifested uniformly among individuals that show it
219
Central dogma
The two step process transferring of information from DNA to protein (DNA transcription --> Translation --> protein)
220
Genes encode
One of five known types of RNA
221
Five known types of RNA
```
snRNA
rRNA
tRNA
mRNA
Pre-miRNA
```
222
snRNA
Participates in sliceosome (stays inside nucleus)
223
rRNA
Ribosomal RNAs transcribed from one of the DNA strands of a gene and provide structural support/catalyze chemical reaction in which amino acids are covalently linked (part of ribosome in cytoplasm)
224
tRNA
Carry amino acids to complex to allow expansion of polypeptide chain (part of ribosome in cytoplasm)
225
mRNA
Messenger RNA assembled as a complementary copy of one of the two DNA strands
Nucleotide sequence is complimentary to the of the gene from which it is transcribed
Allows cells to separate information storage from information utilization
Analogy: You make a copy of a page in your textbook so that you can carry the information around with you without carrying textbook so that you don't lose it
(nucleus and cytoplasm)
226
Pre-miRNA
Bind to regions (typically 3' end) and prevent transcription/translation (work in cytoplasm)
227
Hydroxyl group on 2' C of ribose
RNA
228
Template strand
The DNA strand that is copied in transcription to produce a complementary strand of RNA
229
Non-template strand
The nontranscribed strand of DNA in transcription that will have the same sequence as the RNA transcript except that T is present at positions where U is present in the RNA transcript
230
DNA template
3' to 5' direction
231
RNA is transcribed
5' to 3' direction
232
RNA polymerase
Enzyme that catalyzes the synthesis of RNA
233
During transcription the DNA double helix
Is locally unwound
234
Differences between RNA and DNA?
```
RNA uses a ribose sugar, DNA uses a deoxyribose sugar
RNA uses Uracil, DNA uses Thymine
RNA is unstable, DNA is stable
RNA is transcribed from DNA
Protein is translated from RNA
```
235
Why is RNA unstable?
You don't want mRNA to hang around any longer than it needs to be to be translated so it degrades very rapidly
236
How does transcriptional machinery know where to begin?
RNA polymerase has to recognize code in DNA
237
TATA box
A conserved promoter sequence that determined the transcription start site for eukaryotes
238
Initiation and termination of transcription in prokaryotes and eukaryotes
Are significantly different
239
Promoter
A nucleotide sequence to which RNA polymerase binds and initiates transcription
240
Transcription in prokaryote
Initiation: mRNA starts at position 1 , 10 and 35 nucleotides upstream there are promoter regions
Elongation: genes are closely spaced and several can be encoded on a single RNA molecule
Termination: Transcription terminator sequence (Poly A track and hairpin loop) hint for polymerase to jump off
241
Transcription terminator sequence
Signals end of transcription
242
Introns
Noncoding sequences located between coding sequences
243
Pre-mRNA
Introns present
244
Mature mRNA
Introns are removed
245
Exons
(Both codon and noncoding sequences) are composed of the sequences that remain in the mature mRNA after splicing
246
Transcription factor
A protein that regulates the transcription of genes
247
TATAAT sequence
An AT-rch sequence in prokaryotic promoters that facilitates the localized unwinding of DNA and the initiation of RNA synthesis
248
Eukaryotic transcription
Initiation: Transcription factor binds to TATA box (promoter region) in order to help assemble transcription machinery
Elongation
Termination: Enzyme cuts strand of RNA, a 5' cap is added, a tail Poly-A tail is added at the 3' end of the strand, introns are spliced out
