1
Q
Mendel’s Experiments:
A
Mendel crossed pea plants with contrasting traits (e.g., round vs. wrinkled seeds). He observed that hybrid offspring (F1) all showed the dominant trait, while recessive traits re-emerged in the F2 generation at a proportion near 3:1
2
Q
principle of segregation
A
i. which says that alleles remain distinct and separate during gamete formation (meiosis). (formed from monohybrid crosses)
3
Q
Principle of Independent Assortment
A
Genes on different chromosomes sort independently of each other during gamete formation.
- learned from dihybrid crosses
4
Q
Transmission genetics
A
Studies inheritance patterns and relationships between genes and chromosomes (classical Mendelian genetics).
5
Q
Mendelian inheritance
A
The basic principles of how traits are passed from one generation to the next, such as segregation and independent assortment.
6
Q
Dominance and recessiveness
A
The observation that some alleles mask the effect of others in a heterozygous individual.
7
Q
Genotype and phenotype
A
The distinction between an organism’s genetic makeup (genotype) and its observable traits (phenotype).
8
Q
Genetic linkage
A
The tendency of genes located close together on the same chromosome to be inherited together.
9
Q
Molecular genetics
A
Explores chemical structure, organization, and function of genes.
10
Q
DNA replication
general definition
A
The process by which a cell duplicates its DNA
11
Q
population genetics
A
Focuses on the genetic makeup of populations and how frequencies change over time
12
Q
Gene Expression
A
Gene’s information is used to synthesize a functional gene product, like a protein
13
Q
Transcription and translation
A
flow of genetic information from DNA to RNA and then to proteins
- “central dogma”
14
Q
Mutation
A
changes in the DNA sequence that can alter a gene’s function and introduce a new genetic variation
15
Q
Genetic recombination
A
swapping of nucleic acid sequence between different sources
- swapping of genetic information between two different chromosomes or DNA that leads to a new recombination of genes
16
Q
Gene flow
A
transfer of alleles between populations through migration
17
Q
genetic drift
A
random changes in allele frequences especially in small populations
18
Q
Hardy-Weinberg equilibrium
A
A principle stating that allele and genotype frequencies will remain constant in the absence of evolutionary forces
19
Q
Structure of DNA
A
double stranded helix with deoxyribose (lacks OH compared to ribose), 5 carbon sugar with nitrogenous bases (GTAC)
- double stranded makes it more stable and therefore more suited for long term information storage
20
Q
Structure of RNA
A
Single stranded molecule that uses ribose (which has one more oxygen than deoxyribose); 5 ringed carbon with nitrogenous bases GUAC
- unstable bc of single strand but thats okay because its a temporary copy of genetic infromation
21
Q
Purpose of DNA
A
Stores the genetic blue print of an organism, passed down from parents to off spring.
22
Q
Purpose of RNA
A
Primary role in protein synthesis
23
Q
Environment Genetics
A
plays a crucial role in gene expression, influencing whether genes are turned “on” or “off” and how they function, a process known as epigenetic
24
Q
Characteristics of a model system
A
- short generation time
- small size
- high number of offspring
- inexpensive and easy to maintain
- readily available
- distinct strains between wild type and mutant
25
Similarities in prokaryotes and eukaryotes genetic systems
1. both use dna in their genetic material
2. both use ribosomes to synthesize proteins
3. information flows from DNA to RNA to protein
4. DNA replication proceeds in the 5' to 3' direction
26
differences in prokaryotes and eukaryotes genetic systems
Eukaryotes have multiple linear chromosomes located within a membrane bound nucleus. DNA is also packaged with histone proteins.
- have membrane bound organells
- larger and more complex
Prokaryotes possess a single circular chromosome located in a region of the cytoplasm called the nucleoid (not enclosed in a membrane)
- no membrane bound organelles
- smaller and structurally simpler
27
How did Mendel do his crosses?
He either self pollinated or cross pollinated
- created true breeding lines (P generation) (homozygous)
- Performed monohybrid crosses, produced F1
- allowed the F1 generation to pollenate, creating the F2 generation
28
Traits studied by Mendel
1. plant height
2. flower color !
3. flower position
4. pod shape
5. pod color !
6. seed shape !
7. seed color !
29
Dihybrid Cross
- To test if different traits were inherited together, Mendel crossed true-breeding parental plants that differed in two characteristics.
- self pollinated F1 generation produced a ratio of 9:3:3:1
30
Mitosis
Purpose is to produce two genetically identical diploid daughter cells for growth and repair.
31
Prophase
chromosomes condense and mitotic spindles begin to form
32
Metaphase
chromosomes line up at the cell's equator
33
anaphase
sister chromatids are pulled apart to opposite poles of the cell
34
telophase and cytokinesis
two new nuclei form and the cell divides into two idential daughter cells
35
Meiosis
produce four unique haploid gametes
36
When does DNA replication occur?
before meiosis 1
37
Meiosis 1
(DNA replication is prior so homologous chromosomes have sister chromatids) Cell begins as diploid (2n), homologous chromosomes pair up forming a tetrad and exhancge genes through crossing over. They are then lined up and seperated into 2 haploid (1n) cells.
cell starts with 4 homologous chromsomes
end result is 2 per cell.
38
Meiosis II
the sister chromatids within these two haploid cells separate similar to mitosis, resulting in four genetically UNIQUE haploid daughter cells.
39
unwinding
Helicase unwinds the DNA double helix by breaking the hydrogen bonds between base pair
40
Priming
primase adds short RNA primers to the template strand to give a starting point to DNA polymerase
41
leading vs lagging
leading: 5' to 3' direction, continuous synthesis
lagging: synthesized discontinuously in short fragments called okazaki fragments
42
synthesis
DNA polymerase adds new DNA bases to the 3' bend of the new strand, building in the 5' to 3' direction
43
sealing
ligase seals the games between okazaki fragments, RNA primers are replaced with DNA bases and boom two semi identical semi-conservative short fragments.
44
Chi-Squared calculation
X^2 = (Observed - Expected)^2 / expected + ...
you want your P values to be less then 0.05
45
Complete Dominance (monohybrid cross)
dominant allele completely masks the recessive allele in heterozygous individuals
46
Complete Dominance (dihybrid cross)
results in a 9:3:3:1 phenotypic ration where 4 different phenotypes are observed
47
Incomplete dominance
neither allele is fully dominant over the other, resulting in a blending of the two parental traits
48
incomplete dominance in monohybrid cross
three genotypes produce 3 different phenotypes,
- 1:2:1 ratio where 1 dominant, 2 intermediate and 1 recessive
ex: wavy hair as a result of curly and straight hair
49
incomplete dominance in dihybrid crosses
pheonotypic ratio will be modified as the intermediate appears for each trait
50
Codominance
when two different alleles are both fully expressed in the phenotype of a heterozygous individual
51
codominance in monohybrid croses
| changes in the ratio and a human example
three genotypes produce 3 distinct phenotypes 1:2:1 ratio, similar to incomplete where each group has a unique phenotype
ex: human blood
52
Dihybrid cross codominance
alters the 9:3:3:1 phenytic ratio
ex: human blood ABO with additon of the Rh factor.
53
Epistasis
a gene interaction where one gene modifies or masks the expression of another gene at a different locus
ex: albinism
54
Multiple alleles
presence of more than two alleles for a particular gene within a population, although an individual can only carry 2
ex: human blood types
55
XX/XY systems
The one found in humans and other mammals; males have the XY chromosomes (hemizygous) while women have XX (homozygous)
- Y chromosome carries the SRY gene which initiates the development of male traits
56
ZZ/ZW system
- seen in birds, snakes and sometimes butterflies
females are the hemizyous ones (ZW)
males are the homozygous ones (ZZ)
57
XX/XO system
in this system males only have 1 X chromosome (XO) while females have XX
58
Environmental Sex Determination (ESD)
environment cues dictate sex instead of gene
- temperature dependent where the sex is determined by incubation temp of eggs
- green spoon worms where larvae become female is they land alone on the sea floor, but male is they land in contact with a female.
59
Penetrance
the probaility that a gene will manifest itself phenotypically.
60
incomplete penetrance
some individuals with the gene variant will display the trait while others will not
ex: polydactyly
61
complete penetrance
every individual who carries the genotype will express the associated phenotype
ex: Huntington's disease
62
Penetrance calculation
penetrance = (number of individuals with the genotype who express the phenotype) / (total number of individuals with the genotype)
63
Hershy-Chase Experiment
Used radioactive isotopes of phosphorus and sulfur as a tracer as the molecule with the isotope would be radioactive. DNA used phosphorous and the protein used sulfur.
- radioactive phosphorous in the phages showed DNA transfered
64
Griffith's experiment
Reported in 1928 by Fredrick Griffith, was the first experiment suggesting that bacteria are capable of transferring genetic information through a process known as transformation.
1. live R (rough) strain injected into mice: Mice Lived (strain was harmless)
2. Live S (smooth) straigh in injected: mice died (harmful strain)
3. heat skilled S strain injected into Mice: mice live (bacteria was dead)
4. heat killed S strain mixed with live R strain: Mice died
Griffith discovered the R strain had transformed into the S strain and thus was able to kill the mice. Coined the "transforming principle"
65
transforming principle
A conclusion made by Griffith; a substance that was responsible for transformation. We now know this to be DNA.
66
Avery, MacLeod, and McCarty Experiment
Provided evidence that the transforming principle and genetic information resides in DNA.
- treated cultures with RNase (destroys RNA) and Protease (destroys protein) and DNase (destorys DNA)
- no effect on transformation with RNase and Protease, but the one with DNase did not
- DNase destroyed the transforming principle (DNA), so DNA has the genetic material.
67
DNA replication
| Detailed Steps
1. DNA unwinds at the origin of replication
2. **Helicase** opens the DNA forming replication forks
3. single stranded proteins coat the DNA around the **replication fork** to prevent rewinding
4. **topoisomerase** binds at the region ahead of the replication fork to prevent super coiling
5. **primase** synthesizes the RNA primers complementary to the DNA strand
6. **DNA polymerase III** starts adding nucleotides at the 3'-OH end of the primer
7. elongation of both strands
8. RNA primers are removed by **exonuclease** activity
9. gaps are filled by **DNA pol I by adding dNTPs**
10. Gap between DNA fragments is sealed by **DNA ligase**
68
DNA pol I
Removes RNA primer and replaces it with newly synthesized DNA
69
DNA pol III
Main enzyme that adds nucleotides in the 5'-3' direction
70
Helicase
Opens the DNA helix by breaking hydrogen bonds between the nitrogenous bases
71
Ligase
Seals the gaps between the Okazaki fragments to create one continuous DNA strand
72
Primase
Synthesizes RNA primers needed to start replication
73
Sliding clamp
Helps to hold the DNA polymerase in place when nucleotides are being added
74
Topoisomerase
Helps relieve the strain on DNA when unwinding by causing breaks, and then resealing the DNA
75
Single-strand binding proteins (SSB)
Binds to single-stranded DNA to prevent DNA from rewinding back.
76
dNTPS
DNA polymerase uses to construct new DNA strands during replication by linking them together via phosphodiester bonds , replacing the RNA primers.
- New DNA is synthesized from dNTPS, in polymerisation
- 2 phosphate groups are cleaved and the resulting nucleotide is added to the 3'-OH
77
How is RNA Replicated?
Through transcription
78
Ribosomal RNA (rRNA)
protein subunit that make up the ribosome, the site of protein assembly (cytoplasm)
79
Messenger RNA (mRNA)
carries the coding instructions for a polypeptide chain from DNA to a ribosome (cytoplasm and nucleus)
80
pre-messenger RNA (pre-mRNA)
larger precursor molecules that are the immediate product of transcription in eukaryotic cells.
- they are modified intensely before becoming mRNA and exiting the nucleus (nucleus)
81
Transfer RNA (tRNA)
Link between sequence of nucleotides in mRNA molecules and the amino acid sequence. (cytoplasm)
82
Additional classes of RNA molecules found in the nuclei eukaryotic cells
1. Small nuclear RNAs (snRNAs)
2. small nuclear ribonucleoproteins (snRNPs)
3. small nucleolar RNAs (snoRNAs)
83
Small nuclear RNAs (snRNAs)
found in the nuclei
- processing of pre-mRNA by actively splicing the pre-mRNA
- recognizes splice spots
84
small nuclear ribonucleoproteins (snRNPs)
found in nuclei; When snRNAs combine with protein subunits
- critical component of splicesomes
- functions in the processing of pre-mRNA through intron removal
85
small nucleolar RNAs (snoRNAs)
found in the nuclei of eukaryotes;
- guide the chemical modification of rRNA, tRNA, snRNA
- functions in the processing of rRNA and in the assembly of ribosomes
86
RNA molecules found in the cytoplasm of eukaryotic cells
1. microRNAs (miRNAs)
2. small interfering RNAs (siRNAs)
87
microRNAs (miRNAs)
21-22 bp in length
- overall: inhibit the translation of mRNA
- produced endogenously (made in cell naturally)
- inhibits the translation of mRNA by blocking translation of the target mRNA
-does **imperfect pairing** so it can inhibit the translation of multiple mRNA targets (nonspecific)
- regulates the expression of genes that are alike or those genes having the same origin
88
small interfering RNAs (siRNAs)
21-25 bp;
- overall: triggers degradation of other RNA molecules
- often produced as a result of an infection (not naturally occuring)
- bonds PERFECTLY to target mRNA
- triggers degradation of other RNA molecules.
- induces degradation of the target mRNA through cleavage through perfect base pairing.
- regulates the expression of varying genes by causing gene silencing
89
RNA interference (RNAi)
a process in which small RNA molecules help trigger the degradation of mRNA or inhibits its translation into protein. (gene silencing)
90
Piwi-interacting RNAs (piRNAs)
- overall: surpressing the expression of transposable elements (jumping genes) in reproductive cells
91
Long non-coding RNA (lnRNA)
long RNA molecules found in eukaryotes that do not code for proteins but provide a variety of functions like regulating gene expression
92
CRISPR RNAs (crRNAS)
found only in PROKARYOTES; they assist in the destruction of foreign DNA molecules.
93
Promoter
DNA sequence that transcription apparatus recognizes and binds to initiate transcription. It indicates the direction of transcription, which strand is to be read as the template and the starting point of transcription.
94
Core promoter
located upstream of the gene and is the site to which the basal transcription apparatus binds
- includes the TATA box (found at -25 to -30)
95
Regulatory Promoter
located immediately upstream of the core promoter; transcription factors bind to these sequences and either directly or indirectly make contact with the basal transcription apparatus and affect the rate at which is initiated.
96
Internal Promoters
found downstream of the start site and are transcribed into the RNA
97
5' untranslated region (5' UTR)
sequence of nucleotides in the 5' end of the mRNA that does not encode any of the amino acids of a protein
98
protein coding region
second primary region of mRNA, compromises of codons that specify the amino acid sequence of the protein
99
3' untranslated region (3' UTR)
sequence of nucleotides at the 3' end of the mRNA that is not translated into amino acids
100
Addition of the 5' cap
addition of modified guanine added to the 5' end of eukaryotic mRNA.
101
3' cleavage and addition of poly(A) tail
increases stability of mRNA, aids in export of mRNA from the nucleus, facilitates the binding of ribosomes to mRNA
102
RNA splicing
removes non coding introns from pre-mRNA and facilitates the export of mRNA to cytoplasm. Allows for proteins to be produced through alternative splicing
103
RNA editing
Alter nucleotide sequences of mRNA
104
Internal RNA modifications
influences splicing, mRNA degradation and translation.
105
DNA polymerase alpha (Pol α)
Makes a complex with primase and initiates the process of DNA synthesis by placing RNA primers
106
DNA polymerase Delta (Pol δ)
does DNA synthesis on the lagging strand
107
DNA polymerase Epsilon (Pol ε)
DNA synthesis on the leading strand
108
Recessive epistasis
supplementary epistasis; complete dominance at both gene pairs, however when the gene is homozygous recessive, it hides the phenotype of the other gene
- cause 9:4:3
109
Duplicative recessive epistasis
complementary epistasis; when either gene is homozygous recessive it hides the effect of the other gene.
- aaB_ or Abb would cause the same phenotype if either is recessive
- 9:7 phenotypic ratio
110
Dominant epistasis
the expression of one dominant or recessive allele is masked by another dominant gene
kinda like a hiearchy
W-G- or W-g- cause white
wwG- cause green
wwgg - causes yellow
- 12:3:1
111
Duplicative dominant epistasis
Complete dominance at both gene pairs; however, when either gene is dominant, it hides the effects of the other gene
15:1
112
Duplicate interaction epistasis
supplementary epistasis; the presence of either dominant allele (A_B) at the same time produces a distinct phenotype. (A_bb) and (aaB-) produces an intermediate
9:6:1
113
expressivity
variation of how the manifestation of the genotype is; can be mixed with penetrance.
ex: polydactly (the amount of fingers expressed varies)S
114
Telomerase
replicates the ends of eukaryotic chromosomes and can extend the G rich 3' overhang
115
a. non template strand
b. template strand
c. promoter
d. RNA-coding region
e. transcription start site
f. terminator
g. transcription termination sit
*note that the top strand is not always the template strand, just depends on which way the 5' to 3' goes towards, points towards left than top strand. synthesized towards the left, bottom strand.
116
a. -35 consensus sequence
b. -10 consensus sequence
117
sigma factor
controls the binding of RNA polymerase to the promoter
118
holoenzyme
sigma factor binded stably to a promoter
119
consensus sequence
sequence that consists of the most commonly occurring nucleotides in a sequence.
FIVS 308
flashcards
Decks in class (23)
# Cards
-
Chapter 1: Intro to Genetics12
-
Chapter 2: Chromosomes and Cellular Respiration18
-
Chapter 3: Basic Principles of Hereditary31
-
Chapter 4: Sex Determining and Sex-Linked Characteristics28
-
Chapter 5: Extensions and Modifications of Basic Principles32
-
Chapter 10: Chemical Nature of the Gene34
-
Chapter 12: DNA Replication and Recombination42
-
Chapter 14: RNA Molecules and RNA Processing31
-
EXAM 1119
-
Chapter 15: Translation16
-
Chapter 6: Pedigree Analysis20
-
Chapter 7: Linkage, Recombination and Gene Mapping31
-
Chapter 8: Chromosome Variation47
-
Chapter 11: Chromosome Structure and Organelle DNA22
-
Chapter 18: Mutation and DNA Repair48
-
Chapter 25: Population Genetics38
-
Chapter 23: Cancer Genetics25
-
Chapter 9: Bacterial and Viral Genetic Systems29
-
Chapter 16: Bacterial Gene Expression30
-
Chapter 17: Expression in Eukaryotes21
-
Chapter 21: Epigenetics16
-
Chapter 19: Molecular Genetics and Biotechnology19
-
Chapter 20: Genomics6
