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The role of transfer RNA during protein synthesis
Transfer amino acids from cytoplasm to ribosomes. Lines them up.
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Codon
sequence of 3 bases on mRNA
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Anticodon
3 unbounded bases on one end of tRNA
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Transcription
When DNA makes RNA
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Translation
whole process of protein synthesis
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During protein synthesis ribosomes attach to?
Ribosomes attach to mRNA
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What is the enzyme system that catalyzes transcription?
RNA polymersal
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List 3 types of RNA needed for protein synthesis
Messenger RNA, Transfer RNA, Ribosomal RNA
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Protein synthesis terminates at?
When it goes over a stop codon
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The nitrogenous base found in DNA but not RNA
Thymin
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The nitrogenous base found in RNA but not DNA
Uracel
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During the protein synthesis the anticodons or the transfer RNA attached to?
codons on mRNA
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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
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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.
- 1.G1
- 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
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4 stages of Mitosis
- Mitosis occurs in an orderly sequemce pf events
- -Prophase
- -Metaphase
- -Anaphase
- -Telephase
- INNERPHASE-time in the life cycle when its not dividing
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Mitosis
the division of the nucleus into two identical nuclei
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cytokinesis
division of cytoplasm and cytoplasmic organelles into two cells
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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.
- PROPHASE-
- -Nuclear envelope breaks down
- -Nucleoli break down
- -DNA coils and tightens and becomes visible as distinct
- -Spindle begins to form
- METAPHASE:
- -double stranded chromosomes attach to spindle fibers and become aligned along the equatorial plane of the spindle
- ANAPHASE
- -Centromeres split and chromatids separate and single stranded move toward the poles of the spindle.
- TELOPHASE
- -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
- Cytokinesis:
- 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
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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.
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MEOISIS
- -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
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MEOSIS DIFFERS
- 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.
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CELL RESPIRATION
- Chemical energy is taken out of high energy molecules like glucose and put into ATP.
- ADP+P+ENERGY=ATP
- The immediae source of energy for cellular activities?
- ATP to ADP+P+Energy
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Photosynthesis
- 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
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DNA
- -Building blocks
- Nucleotides
- Nucleotide Structure consists of 3 parts
- 1. Deoxyribose(5-C sugar)
- 2.Phosphate group
- 3. One of 4 nitrogenous bases
- Thymine
- Adenine
- Guanine
- Cytosine
- -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
- Adenine-Thymine
- Cytosine-Guanine
- -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.
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RNA differs from DNA?
- 1. Contains ribose in place of deoxyribose
- 2.Contains uracil in place of thymine
- 3.ITs a single stranded molecule.
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RNA synthesis
- -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
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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
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Protein synthesis
- 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.
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THE central Dogma or the typical flow of genetic info in a cell
DNA arrow mRNA arrow Protein arrow Trait
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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
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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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