Chapter 8 Flashcards
What is a gene?
a section of DNA that contains coded information for making a polypeptide and functional RNA
What is the name of the particular position that genes are found in?
Locus
Explain why scientists believe that at least 3 bases code for each amino acid
Only 20 amino acids occur regularly in proteins and each amino acid must have its own code of bases. As only 4 bases are present 3 must code for an amino acid otherwise there wouldnt be enough amino acids
What are 3 bases on DNA called?
a triplet
What are 3 bases on mRNA called?
a codon
What are 3 bases on tRNA called?
an anticodon
Why is DNA known as a degenerate code?
Because most amino acids are coded for by more than one triplet
Why is DNA known as non-overlapping?
Because each base is only read once - for its triplet
Why is DNA known as universal?
Because with a few minor exceptions each organism is made up of the same bases and is read in the same way
List 6 features of DNA
degenerate universal non overlapping always read one way contains stop codes the start of a DNA sequence is always the same triplet that is later removed if not needed
What are introns?
non coding sequences
What are exons ?
coding sequences
Homologous pairs come about because each organism comes about due to the joining or an ____ cell and a ____ cell. Each of these cells has ___ chromosomes consisting of 1 copy of each chromosome. So in the chromosome each each organism has one _____ chromosome and one ______ chromosome which carry the same _____ and have the same l_____ but may carry different ______
egg sperm 23 maternal paternal genes locus alleles
Define an allele
one of a number of alternative forms of a gene.
Define centromere
the region of a chromosome to which the microtubules of the spindle attach via the kinetochore during cell division
Define chromosome
a thread like structure made of proteins and DNA by which hereditary information is physically passed from one generation to the next