Inheritance (DNA Structure and Protein Synthesis) Flashcards
What is the genome of an organism?
The entire set of genetic material in an organism (the entire DNA
What is a gene?
A small section of DNA within an organism
Each gene codes for one protein
These proteins could be structural, like collagen, enzymes, or hormones
Which proteins are produced affects the characteristics of the organism - we are all slightly different because we all have different genes and therefore produce slightly different proteins
Where are genes located?
On chromosones, which are structures made of DNA (so many genes)
These chromosones are found within the nucleus of a cell
In each human cell, there will be 46 (23 pairs) chromosomes, and in gametes there will be just 23 individual chromosones
In other organisms, the number of chromosomes differ
What is the structure of a DNA (deoxyribonucleic acid) molecule?
Two strands coiled around to form a double helix
The strands are made of a sugar-phosphate backbone
The strands are joined together by complimentary nitrogenous bases bonding together through hydrogen bonds
The base adenine will pair with the base thymine
The base guanine will pair with the base cytosine
The process of pairing complimentary bases is essential for processes of cell divison and protein synthesis as each half of the double helix acts as a template to be copied to form a new double helix
Nucleotide is another name for a base
What are triplets of DNA and what do they code for?
A triplet is 3 contiguous base pairs in a gene (so 6 bases in total)
Each triplet codes for one amino acid during protein synthesis
The triplets are non-overlapping, meaning each triplet only codes for one amino acid, and the bases are not shared between triplets (they are independent of eachother)
What is the structure of an RNA (ribonucleic acid) molecule?
Single stranded, so the bases will stick out sideways from the strand
It contains the base uracil instead of thymine
Otherwise it is the same as DNA
What are the two stages of protein synthesis?
Transcription
Translation
What is the process of transcription?
The hydrogen bonds between complimentary base pairs break and the DNA strands will unwind
The gene necessary to produce the wanted protein which is to be transcribed is therefore exposed
An mRNA molecule is built by transcribing one of the DNA strands which comprise the gene
The mRNA molecule will have complimentary bases to that strand (though it will have uracil instead of thymine)
The mRNA molecule escapes through a pore in the nuclear envelope
A codon is the 3 bases on the mRNA which is complimentary to the triplet on the transcribed DNA strand
What is the process of translation?
After leaving the nucleus, the mRNA molecule will attach to a ribosome in the cytoplasm of the cell
There will be free tRNA molecules in the cytoplasm, each with an anti-codon complimentary to the codon of an mRNA molecule on one end, and on the other a site where an amino-acid has binded
The tRNA molecule with a complimentary anti-codon to the codon of an mRNA molecule will bind to the mRNA molecule
More mRNA molecules will attach to the ribosome in the correct order to form the correct protein, with complimentary tRNA molecules attaching to them
Two mRNA and tRNA molecules can be attached to the ribosome at one time, and a peptide bond will form between the two amino acids attached to the ends of the tRNA molecule
In this way, a sequence of amino acids will be formed to make a protein until an mRNA molecule has a stop codon - at this point the process will stop
The amino-acid binded to the tRNA molecule will be specific to its anti-codon
