T8 DNA, genes and protein synthesis DONE Flashcards
What is a gene?
-section of DNA located at a particular position(locus)
- sequence of DNA bases that codes for polypeptides and functional RNA
How is DNA stored in eukaryotic cells?
-linear DNA molecules that exist the chromosomes
-DNA molecule is wound around proteins called histones proteins (NOT associated mitochondria and chloroplasts)
-DNA molecule is long, so wound up
-fits in the nucleus
How is DNA stored in prokaryotic cells?
-carry DNA as chromosomes
-DNA molecules are shorter and circular
-condenses to fit in the cell by supercoiling
What codes for amino acids?
-sequence of three bases
-triplet or codon
What forms primary structure of a protein?
-sequence of amino acids in a polypeptide
-(single polypeptide chain)
What is a genome ?
-complete set of genes in a cell
What is a proteome?
-full range of proteins that the cell is able to produce
What are exons?
-parts of a gene that do code for amino acids
What are introns?
-sections that don’t code for amino acids
- in eukaryotes are removed during protein synthesis
-prokaryotic DNA doesn’t have introns
What are regions of multiple repeats in DNA?
-in Eukaryotic DNA
-outside of genes
-DNA sequences that repeat over and over
-don’t code for amino acids
What are alleles ?
-slightly different versions of the same polypeptide
-order of bases in each allele is slightly different
What are homologous chromosomes/pair?
-Pairs of matching chromosomes are called homologous pairs
-pair both chromosomes are the same size and same genes, could have different alleles
-alleles found in same fixed position (locus) on each chromosome
What is Transcription?
DNA code is copied into a molecule called mRNA
-In eukaryotes, transcription takes place in the nucleus
-in prokaryotes transcription takes place in the cytoplasm
What is Translation?
-second stage of protein synthesis
-occurs at the ribosomes in the cytoplasm
-amino acids are joined together to make a polypeptide chain (protein)
What is messenger RNA (mRNA)?
-made during transcription
-single polynucleotide strand
-three groups of adjacent bases (codons)
-complementary to the DNA sequence
-carries genetic code from DNA to ribosomes the used to make proteins during translation
What is transfer RNA (tRNA)?
-single polynucleotide strand that’s folded into a clover shape
-hydrogen bonds between specific base pairs
-sequence of three bases at one end(anticodon)
-amino acid binding site on the other end
-carries the amino acids that are used to make proteins and ribosomes
What is the genetic code?
-sequence of amino acids
What is RNAs function?
-transfer genetic information from the DNA to the ribosomes
How does the structure of RNA differ from DNA?
-RNA contains nucleotides with a ribose sugar (not deoxyribose)
-Uracil (U) replaces thymine as a base(U+A)
-nucleotides form a single polynucleotide strand (not a double one)
-RNA strands are much shorter than most DNA polynucleotides
What are the stages of transcription?
-RNA polymerase attaches to the DNA
-Complementary mRNA is formed
- RNA polymerase moves down the DNA strand
-RNA polymerase reaches the stop signal
What happens when RNA polymerase attaches to the DNA in transcription?
-hydrogen bonds between DNA strands in the gene are broken by DNA helicase attached to the RNA polymerase.
-strands separate , DNA uncoils, bases are exposed
-One strands is used as a template for mRNA copy
How is complementary mRNA is formed?
-RNA polymerase lines up free RNA nucleotides alongside the exposed bases on the template strand
-Free bases are attracted to the exposed bases by complementary base pairing
-RNA nucleotides have paired up with their specific bases on the DNA strand, they’re joined together by RNA polymerase forming an mRNA strand
What happens when RNA polymerase moves down the DNA strand?
-hydrogen bonds reform in DNA
-RNA polymerase forms the mRNA strand
What happens when RNA polymerase reaches the stop signal?
-stops making mRNA and detaches from the DNA
-In eukaryotes, mRNA moves out of the nucleus through a nuclear pore and attaches to a ribosome in the cytoplasm
What is pre-mRNA?
-mRNA strands containing introns and exons
-before splicing
What is splicing?
-This takes place in the nucleus before translation
-Introns are removed and the exons are joined together- forming the mRNA strands
What happens in translation?
-mRNA attaches itself to a ribosome and transfers RNA molecules to carry amino acids to it (ATP provides energy for the bond to form)
-tRNA molecule (carrying an amino acid), with a complementary anticodon to the first codon on the mRNA, attaches itself to the mRNA ( complementary base pairing).
-two amino acids attached to the tRNA molecules are joined by a peptide bond
-tRNA molecule moves away, leaving its amino acid behind
-process continues, producing a chain of linked amino acids until stop signal
What is the genetic code?
-sequence of base triplets (codons) in mRNA which code for specific amino acids
-code is non-overlapping
-code is also degenerate (some amino acids are coded by more than one base)
-code is universal (same specific base triplets code for the same amino acids in all living things)
