Unit 1 Key area 1.3 Flashcards
What forms the genetic code?
The base sequence of DNA.
Where is the genetic code found?
This code is found in all forms of life, which suggests that all life originated from a common ancestor.
What are genes?
Genes are the units of genetic code that make up the genotype of an organism.
Why are only a fraction of genes in a cell expressed?
Only a fraction of the genes in a cell are expressed depending on the proteins required by that cell.
Explain what processes are regulated to control gene expression.
Gene expression occurs when a gene is actively coding for a protein within a cell, regulated by the processes of transcription and translation.
Name the molecules in a RNA nucleotide.
ribose sugar, base, phosphate.
Name the differences between DNA and RNA.
RNA is a single stranded molecule
Rna has the base uracil instead of thymine
RNA has a ribose sugar
RNA molecules are much smaller than DNA.
What are the three types of RNA?
Messenger RNA (mRNA) Transfer RNA (tRNA) Ribosomal RNA (rRNA)
Describe messenger RNA
mRNA are formed in the nucleus, it carries a copy of the genetic code from the DNA in the nucleus to the ribosomes in the cytoplasm.
Describe Transfer RNA.
they are molecules in in the cytoplasm which carries specific amino acids to ribosomes, where they can be assembled to form polypeptide chains.
Describe Ribosomal RNA.
RNA (rRNA) is combined with proteins to make up the structure of ribosomes.
What are introns?
Introns are regions which do not carry information about protein synthesis, often known as “junk” or non-coding regions.
What are exons?
Exons are regions of a nucleic acid molecule which are active in gene expression, and are known as coding regions.
Different proteins can be expressed from the same gene due to what?
alternative RNA splicing and the various types of post-translational modification that can occur.
