Lesson 1 Flashcards
What is the central dogma of genetics
Genetic information flows from DNA → RNA → proteins
What is the study of stable phenotypic changes that do not involve alterations in the DNA sequence
Epigenetics
What does epigenetics most often involve
Changes that affect gene activity and expression
What can the poly A tail be compared to in genes
A dress → they can express them differently in different tissues
Is dna replication faster In bacteria or mammals
Bacteria
Why is dna replication faster in bacteria?
There are no chromatin, nucleosomes, and chromosomes but only a circular double strand dna (does not need to be unfolded)
What are the two types of antibodies
Polyclonal and monoclonal
How are polyclonal antibodies obtained?
By injecting the antigen into an animal and then isolating them
How are monoclonal antibodies obtained?
By hybridomas: antibody-producing B cells fused with myeloma cells
Besides the use of antibodies, what is another way to study proteins?
Proteomics: allows us to have a full picture of proteins produced by a tissue
If a psendogene expresses a protein, it is not a psendogene but a:
Gene
What are housekeeping proteins?
Constitutive proteins that are required for the maintenance of basic cellular functions: they are expressed in all cells
Housekeeping proteins represent what percentage of the total protein mass of a cell?
75%
What is one key reason it is easier to analyze DNA / RNA compared to proteins?
They can be hybridized → proteins do not have a complimentary strand
What are the main technologies used to analyze mRNA?
Differential hybridization
Subtractive hybridization
Differential display
Expressed sequence tag (EST)
Serial analysis of gene expression (Sage)
What mRNA technology is used to identify genes that are expressed in one type of cell but not another → ex: normal vs. cancer cells
Differential hybridization
What are the two pitfalls of the differential hybridization method?
It is not possible to detect most genes (low sensitivity) and there is a lot of redundancy in sequences (genes that are more expressed are going to occupy most of the plaque)
Which approach in analyzing gene expression involves the subtraction of a test DNA sample from a reference DNA sample → a tumor cell from a normal cell?
Subtractive hybridization
In which mRNA analysis method is mRNA extracted from normal cells and reverse transcribed into cDNA, amplified by PCR, and then ran on a polyacrylamide gel next to cDNA for the tumor cell mRNA
Differential display
What is the main use for an EST test when analyzing mRNA?
Can be used as probes to detect whether or not a gene is expressed
When using SAGE a short sequence of DNA / RNA contains sufficient information to uniquely identify what?
A transcript and to locate a sequence in the genome
When using SAGE, sequence tags can be linked together to form what?
Long serial molecules that can be cloned and sequenced
What does the quantitation of the number of times a particular tag is observed mean in SAGE?
Provides the expression level of the corresponding transcript
Describe how microarrays are used to analyze mRNA:
The mRNA of 2 different cells is transformed into a single cDNA tagged with fluorescent dye and combined to hybridize microarrays counting thousands of known gene sequences
What are some issues found with microarray analysis?
Sensitivity and range (signals saturate very quickly) and it is difficult to Keep track of the identity of all cDNA
