Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
27 Cards in this Set
- Front
- Back
What is a gene? |
A section of DNA that codes for polypeptides/functional RNA in the form of specific base sequences |
|
How do genes determine the development of organisms? |
Genes code for polypeptides=form proteins=form enzymes=control chemical reactions for organisms development/activities - genes determine nature/development of all organisms |
|
What is the locus of a gene? |
The specific position of a section of DNA |
|
Why must there be a minimum of 3 bases that code for a specific amino acid? |
- 20 different amino acids regularly occur in proteins - Each amino acid is coded by bases - If 1 base=amino acid: Only 4 different amino acids - If 2 bases=amino acid: Only 16 - If 3 bases=amino acid=64 different amino acids=satisfy requirements |
|
What are the features of the genetic code? |
- Degenerate code: Most amino acids are coded by 2-6 triplets - triplet code always read in one direction along the DNA strand - Start of DNA sequence always the same triplet - 3 triplets are stop codes - Code is non-overlapping (each base only read once) - Code universal=same in all organisms (evidence for evolution |
|
What are exons? |
A sequence of bases which code for amino acids |
|
What are introns? |
Sequences of bases which doesn't code for amino acids |
|
What are the differences between prokaryot and eukaryot DNA? |
Prokaryot: Short molecules/form a circle/no associated with proteins/no chromosomes Eukaryot: Longer molecules/Linear/Associated with histones(chromosomes)/DNA in mitochondria and chloroplasts similar to prokaryot DNA |
|
What are homologous chromosomes? |
A set of chromosomes in sexually produced organisms where each pair of chromosomes is half from the mother and half from the father - chromosomes carry the same gene but not necessarily the same alleles |
|
What is the diploid number? |
The number of individual chromosomes |
|
What is an allele? |
The alternative forms of a gene (2 alleles per gene) - one allele comes from each parent/can be same or different |
|
What happens if the alleles of a gene are different? |
Each allele has a different base sequence and so produce different polypeptides |
|
What is a codon? |
A sequence of three bases on mRNA that code for a single amino acid |
|
What is a genome? |
A complete set of genes in a cell, including the genes in the mitochondria/chloroplasts |
|
What is a protenome? |
The proteins produced by a given type of cell under a certain set of conditions |
|
What is a complete protenome? |
The full range of proteins produced by a genome |
|
What are the two types of RNA involved in protein synthesis? |
mRNA and tRNA |
|
What is mRNA? |
A long strand of mononucleotides in a single helix/base sequence determined by DNA base sequence/leaves nucleus to cytoplasm/binds with ribosomes/template for protein synthesis |
|
What is tRNA? |
Small molecule of 80 nucleotides/single strand chain in four leaf clover shape/end that extends=binds to amino acid/each type binds to different amino acid/anticodon=specific to amino acid/anticodon complements mRNA codon/structurally suited to line up amino acids |
|
Give a short summary of protein synthesis. |
- DNA provides instructions for a sequence of bases - Complementary pre-mRNA made through transcription - pre-mRNA spliced to form mRNA - template for tRNA to form polypeptide (translation) |
|
What is transcription? |
The process of making pre-mRNA using a DNA strand as a template |
|
Describe the process of transcription. |
- Enzyme causes DNA strands to separate, exposing bases - Template strand pairs with free complementary bases/RNA polymerase joins free bases into pre-mRNA molecule - DNA strands rejoin behind RNA polymerase (12 bases exposed at one time) - RNA polymerase reaches stop codon on DNA=pre-mRNA complete |
|
Describe the process of splicing pre-mRNA. |
- DNA in eukaryots made of exons and introns - Introns would prevent synthesis of a polypeptide chain - Intron base sequences removed/exons joined together to form mRNA |
|
How many types of tRNA are there? |
60 different types, each type has a specific anticodon and attaches to a certain amino acid |
|
Describe the process of translation. |
- ribosome attaches to mRNA start codon - tRNA with complementary anticodon move to ribosome and pairs with mRNA codon (carries specific amino acid) - tRNA complementary to next codon attaches to mRNA, carrying another amino acid - Two amino acids join by peptide bond (enzyme/ATP) - Ribosome moves to third codon=links amino acids on second and third tRNA - First tRNA released=collects another amino acid - Continues until ribosome reaches stop codon |
|
What are the different ways that proteins are assembled? |
- polypeptide coiled/folded=secondary structure - secondary structure folded=tertiary structure - different polypeptide chains+prosthetic group link=quarternary structure |
|
What is the role of ATP in translation? |
- provide energy to attach amino acids to tRNA - provide energy to attach amino acids together |