Deck 1 Flashcards
Describe complete dominance
Heterozygous phenotype same as that of homozygous dominant (
Describe incomplete dominance
Heterozygous phenotype intermediate between the two homozygous phenotypes (flower color)
Describe codominance. Example?
Both phenotypes expressed in hetereozygotes. Human blood cell
Describe multiple alleles. Example?
Some genes have more than two alleles. Human blood type (IA, IB, i)
Describe pleiotropy
One gene affects multiple phenotypic characters
Epistasis
Many genes influence a single trait
What cross did Mendel perform to discover law of independent assortment?
Dihybrid cross
Condition for independent assortment
Genes on different chromosomes
Marfan Syndrome is an example of _____
Genetic pleiotropy
Labrador Retriever coat color is an example of _____
Epistasis
Units for map units
cM (centi Morgans)
Frequency of recombinant offspring directly correlates to _____
Distance between two genes
Name the scientist that contributed to gene mapping
Alfred Sturtevant
Hemizygote
Having one member of chromosome pair rather than two
Describe the chromosomal differences in bacteria and eukaryots
Bacterial chromosomes are circular and associated with smaller amount of protein
Eukaryote chromosomes are linear and associated with larger amount of protein
Chromatin
Complex of DNA and protein
Name of component used for first level of packing in protein
Histones
DNA is a polymer made up of _____
Nucleotides
Proteins are composed of _____
Amino acids
3 steps to achieve protein synthesis
- mRNA synthesis in nucleus
- mRNA moves outside the cytoplasm
- mRNA is translated by ribosomes to make proteins
3 scientists responsible for study on DNA
Watson, Crick, Franklin
Describe three components of nucelotide
- Nitrogenous base
- Phosphate group/backbone
- 5-carbon sugar
Nucleotide variation in DNA and RNA
DNA: ACTG
RNA: ACUG
Pyrimidines
Single ring, Cytosine, uracil, Thymine
Purines
Double ring, Adenine, Guanine
Bond connecting phosphate backbone in DNA
Phosphodiester bonds
What is the 5’ group called
Phosphate group
What is the 3’ group called
Hydroxyl group
In which location does ribose and deoxyribose differ in
2’. Ribose has -OH, while deoxyribse has -H
Draw the structure if ribose and deoxyribose
.
In which direction is the sequence of DNA written?
5’ -> 3’
Is “primary structure of DNA” single or double-stranded?
Single-strand of nucleotide sequences
Structure of nitrogenous bases
.
Clues about spacing
- Space between helixes was known (X-rays)
- # ’s equal (purines = pyrimidines)
Chargaff’s Rules
- # ’s equal (T = A)
- # ’s equal (C = G)
Name of bond responsible for holding nitrogenous bases together
Hydrogen bonds (enol, keto), H - O, H - N, respectively
Which nitrogenous base bonds are stronger? Why?
C - G stronger than A - T because the former has 3 hydrogen bonds while the latter has 2.
4 enzymes involved in DNA replication
- (RNA) Helicase
- Primase
- DNA polymerase
- Ligase
Where does DNA replication start
3’ end of TEMPLATE strand
Mutation
Any permanent changes in DNA
What enzyme has main proofreading activity
DNA polymerase
Diseases causes by errors in proof reading mechanisms
- Lynch syndrome (autosomal dominant)
- Xeroderma pigmentosum
Two types of mutations . Which one is passed on?
- Somatic mutations
- Gametic mutations
Gametic mutations are passed on
- caused by mistake in DNA replication during meiosis
Huntington’s disease is an example of _____ . Willams Syndrome is also an example of this mutation.
Autosomal dominant mutation
Example of autosomal recessive mutation
Cystic fibrosis, tay-schs disease
Human mutation rate
1.5 * 10^(-8)
Human haploid genome size
3.3 billion base pairs of nucleotides
Central dogma
DNA -> RNA -> protein
Transcription, translation
Example of reverse transcription
HIV
What are coding regions of a gene called
Exons
Are both exons and introns present in pre-mRNA?
Yes
Do point mutations always alter amino acid
Not always. May or may not
Four types of genetic mutation
- Point mutation
- Frameshift mutation
- Chromosomal rearrangements
- Gene duplication
Five types of structural mutation
- Duplication
- Deletion
- Inversion
- Fission
- Fusion
