Biological Molecules and Enzymes Flashcards
sphingosine
like phosphoglycerides except that the glycerol is amino alcohol
Lipoprotein
Function and composition
fat carrier in the blood
hydrophobic core surrounded by phospholipids and apoproteins
T/F In absence of insulin, only brain and liver can absorb glucose
True
Starch
Glycogen for plants
Amylopectin and amylose
alpha linkage
Differentiate between nucleoside, nucleotide, and nucleic acid
Nucleoside - without phosphate (just nitrogenous base and sugar)
nucleotide - with the phosphate
nucleic acid - polymer with multiple nucleotides
AT, GC number of hydrogen bonds
AT: 2 hydrogen bonds
GC: 3 hydrogen bonds
Epigenetic
Changes made without changes in the nucleotie. ex. methylation
Nucleosome
8 histones wrapped around DNA
chromatin composition
1/3 DNA, 2/3 protein, little bit of RNA
Heterochromatin
tightly coiled and condensed, transcription doesn’t happen
Euchromatin
only coiled during nuclear division.
single-copy DNA
- only one cop of a nucleotide sequence
- regions of euchromatin that are actively transcribed
- Long base sequences
- Low rate of mutation
Repetitive DNA
- Not translated - non coding regions of DNA
- remain tightly coiled in heterochromatin
- Short base sequences
- Higher rate of mutation
Methylation
adding -CH3 on cytosine nucleotide. DNA wound more tightly so there is decrease in transcription
non-coding RNA
regions of RNA that doesn’t code for protein. Responsible for chemical changes in the chromatin structure
Promoter sequence function
Dictates where transcription takes place and how often transcription takes place
Is there a proofreading mechanism in transcription?
T/F: errors in RNA are called mutations
No
Errors in RNA are not called mutations and are not passed onto progeny
Termination in transcription
Termination sequence
Rho protein
T/F activators and repressors only occur in prokarotes
F
Lac Operon: explain the positive and negative control of how lac genes are transcribed
Positive control: Acceleration –> CAP activated by cAMP (secondary messenger); this activates the promoter sequence and allows the initiation complex to form
Negative control: lactose binding to the repressor and taking off the operator. Taking the break off.
The presence of lactose can induce the transcription of the lac operon only when glucose is not present
5’ cap
attachment site during translation
protection from degradation of exonuclease
snRNPs
snurps
ribozme that catalyzes chemical reaction on mRNA
snRNPS + associated proteins - spliceosome
Alternative splicing
omitting exons, adding introns, utilizing various splicing sites
ending at different termination site, using a different promoter and etc - contribute to genetic diversity
Introns function in gene expression
associated with amplified protein production
Destiny of proteins injected into the ER lumen
will become plasma membrane proteins of golgi, lslsome, ER, nuclear envelope, or secreted from the cell
Primse in DNA replication
creates RNA primer to initiate or jump start replication on the lagging strand
How are the primers removed in replication? How are the gaps filled?
RNAse H enzyme removes the primer. The gaps are filled by DNA polymerase
Stop codons
UAA, UGA, UAG
Signal for the large ribosome to join and form an initiation complex in translation
t-RNA carring 5’-CAU-3’ sits on the P site
What happens when a stop codon reaches the A site?
protein known as the release factor attaches
Kinetochore
structure of protein and DNA located at the centromere of the joined chromatids of each chromosome
Transversion vs. transition
Both are base-pair substitutions
Transversion: purine to pyrimidine or vice versa
Transition: convert within purines or pyrimidines
Missense substitution
when a base pair changes a codon
Duplication in chromosomal mutation
When a segment of DNA breaks free and attaches onto a homologous chromosome
Translocation
Segment of DNA exchanged between chromosomes
Transposons
Flanked by flanking sequences, they can excise themselves out from the chromosome and reinsert themselves at another location
A way somatic cell can alter its genetic make up without meiosis
Transposition
Gene linkage
When genes on a chromosome are located close together. The are more likely to cross over together
Synaptonemal complex
Zipped region in chromosomes where genetic materials are being exchanged during meiosis
single cross over vs. double cross over
Single cross over: exchanging genetic information just once
Double cross over: exchange a part of the chromosome then gets a sub section of it back (regains some of the original segment)
Penetrance
Probability of gene being expressed if it is present (binary condition, present or not)
Expressivity
how much the genotype is expressed as a phenotype
degree of expression of a certain trait
Barr body
condensed, Inactive site on the X-chromosome. All but one X-chromosome is inactivated during interphase during gameoteogenesis.
XX - one barr body
XXX - two barr bodies
Hardy-Weinberg equilibrium
Equation to predict allelic frequencies in a population
1) no selection for the fittest organism
2) random mating
3) large population
4) immigration or emigration must not change the gene pool
5) mutational equilibrium
p^2 + 2pq + q^2 = 1
p + q = 1
