Bio Test 3 Flashcards
What’s the structure of DNA?
- Phosphate group,
- Sugar (deoxyribose),
- and a nitrogenous base
Possible nitrogenous bases for a DNA?
- Adenine,
- Thymine,
- Cytosine,
- Guanine
What was Griffins discovery?
- Killer bacteria transform non leathal bacteria to killers.
DNA is responsible for…. not ….
- …transformation… protein…
What DNA bases ALWAYS bind together?
- Adenine always to Thymine
- Cytosine always to Guanine
Why do the same DNA bases always bind together?
- Chargaffs rule:
- Equal nr of bases A and T equal the nr of bases C and G
How are the nitrogenous DNA bases connected?
- By hydrogen bonds
If there are 2000 bases in a chromosome strand and 300 of those are the base Adenine, how many Guanine bases are in the strand?
- 700
- (Reasoning: 300-A/ 300-T/ 1400=C+G→ C-700/G-700)
Explain the process of DNA separation: (4 steps)
- Double-Stranded DNA molecule being replicated
- Strands unwind and separate
- Each strand is a template that attracts and binds complementary nucleotides, A with T and G with C
- Each double-stranded DNA molecule consists of one parental and one daughter strand, as a result of semi conservative replication
Why does DNA split in half? What does it promote?
- Diversity
- Efficiency
If the NDA sequence on one side is TGGCTAAGC, what is the order of the bases that would be added on in replication?
- ACCGATTCD
Enzymes in DNA replication?
- Multiple enzymes and energy are needed
- Repair, and correct mistakes in the process
Where does prokaryotic cell DNA division occur?
- In bacteria and Archaea
Mutation of cells can be…?
- Can be good,
- Can also lead to cell death or cancer
To know about Mitochondrial DNA?
o Circular DNA
o From a single lineage from your mom
o Makes proteins for the Mitochondrion
o We can map a family tree using the mitochondrial DNA
When can cancer form?
- Cancer cells can form when genes coding for proteins that control cell replication are damaged and the cell divides uncontrolled forming a tumor
Components of a Protein-?
- Made up of several 100 amino acids
- Polypeptide strain
- If Amino Acids are ever mixed up from its original order then it will make up a different protein
3 types of RNA:
- Messenger RNA (mRNA)
- Transfer RNA (tRNA)
- Ribosomal RNA( rRNA)
Messenger RNA (mRNA)
- Nucleus, migrates to ribosomes in cytoplasm
- Carries DNA sequence info to ribosomes
Transfer RNA (tRNA)
- Cytoplasm
- Provides linkage between mRNA and amino acids; transfers amino acids to ribosomes
Ribosomal RNA( rRNA)
- Cytoplasm
- Structural component of ribosomes
What is different between mitochondrial DNA and Nuclear DNA with respect to how it is passed down from parent to child?
- Nuclear DNA is inherited from all ancestors
- Mitochondrial DNA is inherited from only the mother
- Mitochondrial DNA is circular.
Organelles and other players involved in protein synthesis?
- DNA,
- messengerRNA,
- transferRNA,
- ribosomalRNA,
- nucleus,
- rough endoplasmic reticulum,
- golgi apparatus,
- cytoplasm,
- amino acids
What are the differences between RNA and DNA?
- RNA is not double stranded,
- RNA does not contain genetic info,
- RNA has eurocel instead of thynem.
- Sugar group, DNA: deoxyribose, RNA: ribose
- Nitrogenous bases: DNA: ATCG, RNA: AUCG
Messenger RNA
- Functions in nucleus
- Migrates to ribosomes in cytoplasm
- Carries DNA sequence info to ribosomes.
Transfer RNA
- Functions is cytoplasm
- Provides linkage between messenger RNA and amino acids: transfers amino acids to ribosomes
Ribosomal RNA
- Functions in cytoplasm
- Structual component of ribosomes
In the nucleus:
- DNA unzips (weak hydrogen bonds between the nucleotide bases)
- RNA nucleotides bind with their complimentary DNA bases
- RNA strand releases from DNA (DNA zips back up)
- RNA is fine tuned by removing the introns (unnecessary nucleotides for the protein): the final RNA strand is now called mRNA and it leaves the nucleus
In the cytoplasm:
- mRNA enters rRNA (ribosome)
- tRNA hooks up with amino acids (one tRNA for one amino acid)
- rRNA is found associated with rough endoplasmic reticulum
- tRNA transfers an amino acid to mRNA based on the 3 letter codon (3 nucleotides)
- - a. T-RNA is important as it picks up a specific amino acid.
- - b. There are multiple codons for most amino acids - completed peptide strand enters rough e.r. then it is sent to the golgi apparatus to
become a completed protein and to find out its final destination.
If the DNA sequence is TACCCTTCAGCA, what would be the mRNA sequence?
• AUGGGAAGUCGU (its mRNA not DNA – so use the U’s)
Why is gene regulation necessary?
- ATP
- Don’t let RNA transcribe DNA
- Most energy saving is stopping transcription at the top
- Regulating protein synthesis
Prokaryotes Vs. Eukaryotes
o Prokaryotes:
- No nucleus
- Bacteria
- Why do we need RNA to code for the amino acids? → the codons for the the amino acids are in the RNA not DNA → there are no U’s but T’s
- No mRNA editing
- Single celled
o Eukaryotes:
• Multicellular
Red blood cells make what?
- hemoglobin
4 different ways to modify protein
- Transcription factors-chromatin and DNA modifications
- Alternative splicing
- mRNA export from nucleus mRNA stability
- protein modifications protein localization
Porto-Oncogene?
- Regulates how fast cell cycle occurs,
- If mutated it is called cancer gene.
Stem cells?
- can be cloned to any cell
eg. Muscle cell, skin cell, etc
Potential uses and problems with gene therapy? (4)
- Insert RNA version of normal allele into retrovirus
- Let retrovirus infect bone marrow cells that have been removed from the patient and cultured
- Viral DNA carrying the normal allele inserts into chromosomes
- Inject engineered cells into patients
• Transgenic Organism:
o Inserting genes from one organism into another organism:
- Gee inserted into plasmid
- Plasmid put into bacterial cell
• Making recombinant DNA:
o Restriction enzme cuts sugar-phosphate backbones
o DNA fragment added from another molecule cut by same enzyme base pairing occurs
o DNA ligase
• Uses of transgenic organisms:
o Plant makes the pesticide so you don’t have to spray with pesticide. When the insect eats the corn it dies due to the toxins within the corn DNA
o vitamin-a deficiency for countries that eat a lot of rice
Therapeutic cloning vs. Reproductive cloning
- Therapeutic cloning: Clone eg skin cells and put it on other places where you need it.
- Reproductive cloning: Taking the nucleus from a reproductive cell and stick it into an egg and tease in.
Knock out a gene?
- stops transcription DNA -> mRNA.
- Usually during the single-cell stage of life just after the sperm and egg fuse = zygote.
- Gene out forever.
Knockdown
- stops translation of mRNA -> protein.
- Makes “Antisense RNA” a complimentary strand to part of mRNA.