3.4.2 DNA and Protein Synthesis Flashcards
How do introns and exons affect protein synthesis?
Introns should not be transcribed or translated
Splicing is when exons are copied, introns are removed
What is mRNA?
RNA that transfers the DNA code from the nucleus to the cytoplasm
Short for messenger RNA
Small enough to leave the nucleus though the nucleus pores and to enter the cytoplasm
What is a codon?
A sequence of three bases on mRNA that codes for a single amino acids
What is the genome?
The complete set of genes in a cell, including those in mitochondria and/or chloroplasts
What is the proteome?
The full range of proteins produced by the genome
Sometimes called the complete proteome, in which case the proteome refers to the proteins produced by a given type of cell under a certain set of conditions
What is the structure of RNA?
Polymer made of repeating mononucleotide sub-units which forms a single strand Nucleotide structure: Pentose sugar ribose One of the organic bases (A, G, C, U) A phosphate group
What are the two types of RNA?
Messenger RNA (mRNA) Transfer RNA (tRNA)
What is the structure of mRNA?
Consists of thousands of mononucleotides
Long strand arranged into a single helix
Base sequence is determined by the base sequence of DNA in transcription
What is the structure of tRNA?
Small molecule
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What occurs during protein synthesis in terms of mRNA?
An anticodon pairs with the three complementary organic bases that make up the codon on mRNA
What are the characteristics of DNA?
Double polynucleotide chain Larger than mRNA and tRNA Double helix Pentose sugar is deoxyribose Organic bases: A, G, C, T Found mostly in the nucleus Quantity is constant for all cells of a species except gametes Chemically very stable
What are the larger steps of protein synthesis?
DNA provides the instructions in the form of a long sequence of bases
Transcription: pre mRNA is formed
Splicing: Pre-mRNA is spliced to form mRNA
Translation: mRNA is used as a template
What is transcription?
The process of making pre-mRNA using DNA as a template
What are the steps of transcription?
DNA helicase breaks hydrogen bonds between the organic bases to expose the nucleotide bases
One strand acts as a template
The template pairs with complementary nucleotides present in the nucleus except A links to U
RNA polymerase moves along the strand and joins nucleotides together to form a pre-mRNA molecule
RNA polymerase adds nucleotides one at a time
DNA strands rejoin behind behind the pre-mRNA
When a stop code is reached by polymerase, it detaches and the pre-mRNA is formed
What are the steps of splicing?
Pre-mRNA is spliced to form mRNA
Introns, which don’t code for proteins, are removed and the functional exons are joined together