Genetic Control Flashcards
Cell function & Inheritance
What are the four characteristics of a genome?
1) . Store information (for life functions)
2) . Express info (in the form of polypeptides to direct life functions; basically an on/off switch) ex hormones
3) . Replicate/reproduce themselves
4) . Variation by mutation (ex: mutation)
What are the purine vs pyrimidine bases? Which ones connect?
Purine- Adenine and Guanine
Pyrimidine- Thymine (DNA) or Uracil (RNA) and Cytosine
A and T or A and U
G and C
What is a genome?
An organism’s full set of genes that is needed for day-to-day function of all it’s cells (distributed in chromosomes)
What are the names of the two DNA strands we need for replication?
Coding strand (copied in transcription)
Non sense strand (not copied for transcription)
***Both used for duplication/replication
What are the four steps/stages of DNA replication?
1) . Double stranded DNA unwinds
2) . The junction of unwound molecules is a replication fork
3) . A new strand is formed by pairing complementary bases with the old/complementary strand
4) . Two complete DNA helices are made; each one has one new and one old strand = “semiconservative”
How many pairs of chromosomes make up DNA?
23 (one from each parent)
What is chromatin? What is the process of DNA turning into chromatin?
It is a coiled structure that is made up by packaging DNA, ribonucleic acids, and proteins called histones together. The histones attach to and compress the double-helical strands of DNA. The chromatin then forms bead-like structures called nucleosomes. These nucleosomes fill the cell nucleus.
When chromatin and histones are paired together, what impact does this have on DNA replication?
DNA cannot replicate now; chromatin has to change its structure in order for it to be “accessible”. This is called chromatin remodeling
What is a triplet codon comprised of and what does it equal?
Comprised of 3 bases (A,C,T, G); one codon equals one “word” of protein recipe (equal one amino acid)
What is the RNA start codon?
AUG
What are the three RNA stop codons?
UAA, UAG, UGA
What are DNA mutations and what are the three main types?
Mutations are accidental errors in duplication
1) . Substitution of one base pair from another
2) . Loss or addition of one or more base pairs
3) . Rearrangement of base pairs (which leads to a non functional codon)
What are five factors that could cause DNA mutations?
1) . Spontaneous
2) . Radiation
3) . Chemicals
4) . Environmental agents (ex: agent orange in veterans)
5) . Inherited : only occurs in GERM cells (sex chromosomes)
What is the most critical enzyme for DNA repair? What type of genes controls this enzyme?
Endonucleases because they recognize the mutations, cleave them out, and replace that area with the correct sequences
EN’s are under control of repair genes (loss of these genes makes DNA more susceptible to mutations)
What two type of genes are mutated in cancer?
proto-oncogenes or suppressor genes
What is the variability of each individual’s genetic sequence (compared to the general population)?
0.1% (accounts for physical traits, behaviors, and disease susceptibility)
What part of DNA comes from the mother? What are three characteristics of this DNA
mtDNA
Double stranded ring (instead of double helix), 37 genes, and mtDNA disorders are rare but commonly effect the neuromuscular system (autism might be new link)
What is RNA responsible for?
Key for protein synthesis
responsible for assembly of biochemical products
RNA characteristics: what type of strand, what are its bases, what is its sugar made of, what is it used for, what kind of properties can it have
Single stranded AGCU (uracil) Sugar is ribose Used for gene expression (more unstable than DNA) Can have catalytic properties
DNA characteristics: what type of strand, bases, what is its sugar made of, what is it used for
Double stranded
Bases: AGCT
Deoxyribose
Used for information storage
What are the three types of RNA
Messenger (mRNA), Ribosomal (rRNA), Transfer RNA (tRNA)
What is the function of mRNA? What process is it formed by? What is its relationship with tRNA?
It carries genetic info from DNA to the ribosome for protein synthesis
It is formed by transcription
tRNA recognizes it and allows the ribosome to form the correct polypeptide chain
What is the function of rRNA? Discuss the size of rRNA
Makes up ribosomes which are “workbenches” for translation of mRNA into protein; translates the instructions and provides the machinery needed for protein synthesis
it is the largest RNA molecule
What is the function of tRNA? discuss its size and what are its two recognition sites
reads the mRNA and delivers the appropriate amino acids to the ribosome
smallest RNA molecule
Recognition sites: one is complementary for the mRNA codon and the second is for its particular amino acid
What is RNA transcription? Where does it occur? What enzyme helps generate the mRNA strand?
Synthesis of RNA from a DNA template to make mRNA(coding strand of DNA is used as template)
Occurs in nucleus
RNA polymerase
What two things do you need for effective transcription?
1). RNA polymerase binds with other factors to form transcription complex
2). Transcription complex binds to promoter region of DNA called TATA box
This activity begins replication and will only stop once it hits a stop codon
What happens during RNA processing?
It adds certain nucleic acids to the ends of RNA strands and splices out other internal sequences
What is splicing?
It is part of RNA processing within transcription
Splicing increases the product from one gene, meaning more than one protein can be made from a single gene sequence
What are exons vs introns?
Both are involved in RNA splicing
Exons are the retained piece of protein coding mRNA sequences
Introns are the pieces between exons (that we remove)
What happens when we get mutations at RNA processing splice sites?
Mutations at these sites can cause altered proteins that can result in a diseased state
Where does mRNA go once its processed?
it diffuses through the nuclear pores into the cytoplasm, where it controls protein synthesis (translation)