!!!⭐️Genetic info, variation and relationships: Genes, DNA and Protein Synthesis (good for genes and proteins OP4103) Flashcards
What are the character of prokaryotic DNA?
Short
Circular
Have no histones present (naked)
Give a piece of evidence that supports the endosybiotic theory
The circular naked loops of DNA that are found in mitochondria and chloroplasts
Give some characteristics of eukaryotic DNA
- molecules are long
- linear
- associated with histone proteins
What does each nucleosome consist of?
A cluster of 8 histone proteins around which DNA is wrapped twice
Give the three steps to how a DNA and its associated protein form a chromosome:
- The DNA double helix wraps around histone proteins forming the nucleosome
- The DNA histone complex coils further and is then wrapped to form the chromosome
- Once the chromosome is visible, the DNA and protein is describes as condensed chromatin
What is the locus of a DNA molecule?
The specific position of each gene
How many chromosomes do humans have?
46
What are homologous pairs?
Pairs of chromosomes where one is the maternal chromosome and the other is the paternal chromosome. They carry the same genes but not necessarily the same alleles
What happens to the homologous pairs in meiosis?
They separate to produce gametes that are haploid
What’s an allele and how do they arise?
It’s one of the different variations of a gene as they each have a slightly different sequence of bases brought upon by mutations
How can mutations have a negative impact on the organism?
Because the changes in the base sequence will mean a different sequence of amino acids are coded for so a different polypeptide and hence a different protein is produced which may not function e.g. if it’s an enzyme and has a different shape it may not fit the substrate and can’t function hence causing consequences for the organism
What do genes of the same species have in common?
They are found on the same locus of the same chromosome
What is a gene?
A base sequence of DNA that contains the coded information for making polypeptides and functional RNA
What is a genome?
The complete set of genes in cells/ all of the DNA of an organism
The gene is a base sequence of DNA that codes for…
-the amino acid sequence of a polypeptide