BIO TEST 2
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The role of transfer RNA during protein synthesis
Transfer amino acids from cytoplasm to ribosomes. Lines them up.
sequence of 3 bases on mRNA
3 unbounded bases on one end of tRNA
When DNA makes RNA
whole process of protein synthesis
During protein synthesis ribosomes attach to?
Ribosomes attach to mRNA
What is the enzyme system that catalyzes transcription?
List 3 types of RNA needed for protein synthesis
Messenger RNA, Transfer RNA, Ribosomal RNA
Protein synthesis terminates at?
When it goes over a stop codon
The nitrogenous base found in DNA but not RNA
The nitrogenous base found in RNA but not DNA
During the protein synthesis the anticodons or the transfer RNA attached to?
codons on mRNA
Describe the cell cycle in prokaryotes including an explanation of binary fission.
- -the cell elongates
- -The DNA duplicates
- -A partition forms in the middle of the cell
- -Then the cell seperates into 2 cells
- -This method of prokaryotic cell division is called binary fission
- -The 2 daughter cells are genetically identical
Describe the 4 phases of the cell cycle in eukaryotes:G1, S, G2, and M
-Three of these phases involve cell growth and one involves cell division.
The three growth stages are called INTERPHASE.
- The growth before DNA replication
- New proteins, ribosomes, mitochondria, and other cell compenents are formed in preparation of DNA synthesis and cell division.
- The length of this cycle determines the length of the entire cell cycle.
- 2.S Phase
- Period of DNA replication
- When S phases ends each chromosome is made up of 2 identical DNA molecules.
- 3.G2 Phase:
- Growth period after DNA replication .
- The cell continues to synthesize proteins.
- It is possible that some of these proteins promote cell division.. When all the necessary proteins have been synthesized cell division begins.
- 4. M Phase: Consists of 2 main events-mitosis and cytokinesis
4 stages of Mitosis
- Mitosis occurs in an orderly sequemce pf events
- INNERPHASE-time in the life cycle when its not dividing
the division of the nucleus into two identical nuclei
division of cytoplasm and cytoplasmic organelles into two cells
Following about Mitosis
- 1. The basic nature
- The mother cell divides into 2 daughter cells and the 2 daughter cells receive the same DNA as the mother cell. So these 2 cells are genetically identical.
- 2. Main characteristics or occurrences of the following stages:
- Interphase:This includes the 3 growth phases-G1, S, and G2
- Characteristics: Nuclear envelope intact
- -Nucleoli intact
- -DNA loosely coiled so occurs chromatin
- -since this includes the S stage, the DNA duplicates during this stage. After it duplicates the chromosomes double stranded, that is they consist of 2 identical DNA molecules.
- -Nuclear envelope breaks down
- -Nucleoli break down
- -DNA coils and tightens and becomes visible as distinct
- -Spindle begins to form
- -double stranded chromosomes attach to spindle fibers and become aligned along the equatorial plane of the spindle
- -Centromeres split and chromatids separate and single stranded move toward the poles of the spindle.
- -Begins with the arrival of the chromosomes at the poles of the spindle.
- -The events are the reverse of prophase
- Nuclear envelopes are reformed.
- Nucleoli reformed.
- DNA becomes loosely coiled forming chromatin.
- Spindle breaks down.
- Distinguish between plant and animal cell mitosis
- 3.In animal cells structures called centrioles form the poles of the spindle. Plant cells lack centrioles
- the division of the cytoplasm and cytoplasmic organelles into 2 cells.
- In animal cells occurs by the formation of a cleavage furrow.
- In plant cells occurs by the formation cell plate
How the end result differs from mitosis?
- Meosis-end result is mother divides into 4 daughter cells with each having half the chromosomes of the mother cell
- Mitosis-end result is mother cell divides into 2 daughter cells with the same chromosomes as the mother cell.
- -A type of cell division characterized by 2 successive divisions with one duplication of the chromosomes resulting in 4 daughter cells having half the chromosomes of the mother cell.
- -Homologus chromosomes
- A pair of chromosomes containing similar pairs of genes throughout their length
- -Distinguish between diploid and haploid cells
- Diploid cell- cell containing 1 of each pair of homologus chromosomes
- -Haploid cell-cell containing one of each pair of homologus
- 1. Synapsis occurs(pairing of homologous chromosomes during meosis)
- 2. Metaphase 1-2 double stranded chromosomes attached to each spindle fiber.
- 3. Anaphase 1-centromeres do not split and doubled stranded chromosoms move to the poles.
- 4. Telophase 1-chromosomes are double stranded.
- BIOLOGICAL SIGNIFICANCE
- f. Necessary for sexual reproduction to prevent doubling of the chromosomes with each generation
- WHEN AND WHERE DOES IT OCCUR?
- g. It occurs in ovaries and testes during the gamae formation.
- Chemical energy is taken out of high energy molecules like glucose and put into ATP.
- The immediae source of energy for cellular activities?
- ATP to ADP+P+Energy
- Equation:6CO2+6H20 to C6H12O6+6O2
- -nearly the reverse of cellular respiration; light enry is trapped and converted to ATP's which is then used to convert CO2 and H2o into sugar and O2 is released as waste product.
- What four conditions are necessary for this process?
- The 2 reactants-CO2 and H2O and light and chloroplasts.
- What are the final end products?
- Carbohydrates and O2
- Biological significance?
- 1. Converts solar energuy to chemical energy making it available to organisms.
- 2. Earths source of O2
- -Building blocks
- Nucleotide Structure consists of 3 parts
- 1. Deoxyribose(5-C sugar)
- 2.Phosphate group
- 3. One of 4 nitrogenous bases
- -Molecular structure of DNA
- The nucleotides attach vertically by the phosphate of one nucleotide bonding to the deoxyribose of another nucleotide.
- The Nucleotides attach horizontally by the H bonds forming between the complimentary bases
- -DNA REPLICATION
- The DNA molecule separates completely into 2 individual strands. Both strands function as a template to synthesize complimentary strands of DNA polymerase is the main enzyme involved.
RNA differs from DNA?
- 1. Contains ribose in place of deoxyribose
- 2.Contains uracil in place of thymine
- 3.ITs a single stranded molecule.
- -The DNA molecule partially separates.
- -One of the partially separated strands functions as a template to synthesize a complimentary strand of RNA
- -As the RNA is formed it separates from the DNA
- -The DNA strands then recombine
- -So the end result is one single stranded RNA moelecule
- -RNA polymerase is the main enzyme involved
3 types of RNA
- -Messenger RNA-a long molecule sonsisting of single strand of 1000 to 10,000 Nucleotides
- -Transfer RNA-clover leaf like molecule consisting of about 80 nucleotides
- -Ribosomal RNA-One of the main structural molecules of ribosomes
- 1. The mRNA is formed on the DNA template in the nucleus and travels to the cytoplasm.
- 2.Through a complex process the mRNA and ribosomes attach.
- 3.The tRNA's move out of the nucleus into the cytoplasm where they attach to their amino acid
- 4. At the point of attachment of ribosome to mRNA, the 1st codon of the mRNA bonds to the anticodon of the first tRNA
- 5.A snd tRNA moves into the ribsome and bonds to the adjacent codon on the mRNA this brings the 1st 2 amino acids side by side
- 6.The bond holding the 1st amino acid to its tRNA is broken and this amino acid immeidately attaches through a peptide bond to the 2nd amino acid which is still attached to its tRNA.
- 7.The ribosome then moves along the mRNA until the next codon of the mRNA is brought into the ribsome.
- 8.The 3rd tRNA with its attached amino acid then bonds to the 3rd codon of the mRNA
- 9.The 2nd tRNA releases its amino acid and it bonds by a peptide bond to the amino acid still attached to the 3rd, tRNA
- 10.This process is repeated as the ribosome moves along the mRNA.
- 11.The process terminates at a specific nucleotide sequence on the mRNA called a stop codon.
- 12.At this pont the polypeptide chain is liberated from the ribosome-mRNA complex into the cytoplasm where it develps into a specific protein.
THE central Dogma or the typical flow of genetic info in a cell
DNA arrow mRNA arrow Protein arrow Trait
An exception to the typical flow of genetic ino
In retro virus HIV the flow of genetic info is as follows:
RNA arrow DNA arrow mRNA arrow Protein
3 different kinds of mutations and causes
- 1. Base substitution mutation
- Simplest kind of mutation.
- One base pair replaces another.
- 2. Base Deletion mutation
- caused by removing a base pair from the DNA.
- 3. Base insertion mutation
- Caused by adding base pairs to the DNA.
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