DNA, Genes and Chromosomes Flashcards
Match the following terms:
A. DNA –> RNA
B. RNA –> Proteins
C. RNA –> DNA
- Translation
- Reverse transcription
- Transcription
A. 3
B. 1
C. 2
What is the site of ribosomal RNA production + assembly?
Nucleus
Nucleus is bounded by inner/outer membrane with _____ _____ where materials move in/out. The outer membrane is connected to the ____ _________.
Nuclear pores
Endoplasmic Reticulum
What are the four phases of the cell cycle?
G1; gap phase 1
S; synthesis
G2; gap phase 2
M; mitosis
Match the following terms regarding the cell cycle:
A. G1
B. S
C. G2
D. M
- Cell prepares for mitosis
- Cell constituents (RNA, lipid, proteins) made, cell increases in size
- Chromosome segregation + division
- DNA replication duplicates each chromosome
G1: Cell constituents (RNA, lipid, proteins) made, cell increases in size
S: DNA replication duplicates each chromosome
G2: Cell prepares for mitosis
M: Chromosome segregation + division
Match the following terms:
A. G1
B. G2
C. M
- Replicated chromosomal DNA
- Unreplicated chromosomal DNA
- Condensed sister chromatids
G1 - Unreplicated chromosomal DNA
G2 - Replicated chromosomal DNA
M - Condensed sister chromatids
The bond A-T has __ H-bonds, while C-G has ___ H-bonds.
2, 3
What are the two purines and the three pyrimidines?
Purines: Adenine (A) + Guanine (G)
Pyrimidines: Cytosine (C), Thymine (T), Uracil (U)
Three key features of nucleotides include:
- base
- pentose sugar; ribose in RNA, deoxyribose in DNA
- phosphate
___________ bond links adjacent nucleotides, while the polynucleotide sequence is always written in _______ direction.
Phosphodiester
5’ –> 3’
What evidence and by who did James Watson and Francis Crick use to propose the DNA double helical structure?
The analysis of DNA fiber X-ray diffraction patterns generated by Rosalind Franklin and Maurice Wilkins
and
Erwin Chargaff’s revelation that the percentages of A=T and G=C
How does the Tata box binding protein (TBP) bend DNA?
Conserved C-terminal of the TBP binds to the minor groove, which is rich in A&T. This bends and untwists DNA.
The ______ the G+C%, the _____ the Tm, breaking the ______ G-C hydrogen bonds requires more energy
than breaking the ___ A-T hydrogen bonds.
greater, greater, 3, 2
What is Tm?
The temperature in which half of the dsDNA bases have denatured.
How does gene family arise?
Duplication of genes during unequal meiosis recombination (crossing over)
What proteins organizes a single DNA molecule into increasing levels of condensation from nucleosomes to higher order
chromatin folding?
Histones and non-histones
T or F. To access any given portion of highly compacted DNA for transcription, replication, and repair of damage, the long DNA molecules must become tangled or broken.
F
What can unequal crossing over during meiosis may result?
exon or gene duplication
*duplicated genes on one chromosome might encode slightly different proteins
What are the two types of eukaryotic transcription units?
- Simple transcription unit (10% of human transcripts)
- Complex transcription unit
T/F. Simple transcription unit is a polycistronic region, that encodes for more than one protein
False.
Simple transcription unit is a MONOCISTRONIC region that encodes for one protein.
Match the following terms regarding mutations in simple transcription unit:
- Mutation in a transcription controlled region
- Mutation in an exon
- Mutation in an intron
a. new splice site -> abnormally spliced mRNA -> mutated protein
b. decreased or no transcription; decreased or no protein
c. abnormal protein with diminished activity
Mutation in a transcription controlled region - decreased or no transcription; less or no protein
Mutation in an exon - abnormal protein with diminished activity
Mutation in an intron - new splice site -> abnormally spliced mRNA -> mutated protein
For complex transcription unit, a transcript can be processed in 3 different ways. Name + define them.
- Alternative splice sites; same outer exons but different internal exons encode PROTEIN ISOFORMS (polycistronic)
- Two poly(A) sites; mRNA with alternative 3’ exons
- Alternative cell-type-specific promoters; one promoter is activated with one exon in one mRNA, and another promoter is activated with another exon in another mRNA.
Mutation in shared control regions/exons affect ____ proteins, while mutations in different control regions/exons affects ___ protein.
Both, One.
Protein coding genes can be solitary or part of family. Gene families encode:
a) protein isoforms with specific physiological functions
b) heavily used gene products that must be transcribed at increased rate
Duplicated genes common in ______ ________. Higher density of protein-coding genes with out introns common in ______ ______ / ___________.
Higher eukaryotes
Lower eukaryotes/prokaryotes
What kind of organisms have a lower gene density with non-coding introns/sequences including long tandem arrays of repeated short sequences?
Multi cellular animal/plant
Match the following terms:
- DNA fingerprinting
- Chromosome painting
A. reveals chromosome defects + evolutionary relationships. can also analyze chromosomal translocations
B. compares individual differences in simple-sequence tandem arrays
DNA fingerprinting - compares individual differences in simple-sequence tandem arrays.
Chromosome painting - reveals chromosome defects + evolutionary relationships. can also analyze chromosomal translocations
Chromatin contains _______ of DNA wrapped around _______ ________.
Nucleosomes
Histone Octamers
What are the four major post-translational modifications on histones that are used to regulate chromatin structure & gene transcription?
- Acetylation
- Methylation
- Phosphorylation
- Ubiquitinylation
Chromosomes are localized in _________ “territories” in the interphase nucleus which each of them are restricted to.
Non-overlapping + territory.
Define nucleosome structure
~145 bp of DNA around octamer protein core with 2. copies of each histones.
Histone surface (+) hold (-) DNA.
DNA wrapped one & 2/3 turns around histone core.
How are nucleosomes arranged in extracted chromatin?
like beads on a string
What is the difference between euchromatic and heterochromatic?
Euchromatin is decondensed & allows cellular components to access the DNA.
Heterochromatin is condensed; super compact.
What is the G-value paradox?
The number of protein-coding genes does not correlate with biological complexity
What is the C-value paradox?
Genome size does not correlate with biological complexity
