(4) genetic information Flashcards
what is the difference between DNA in eukaryotic cells and prokaryotic cells?
eukaryotic DNA: longer, linear
associated w histones (proteins) to form chromatin (substance that makes chromosomes)
(in membrane bound nucleus)
prokaryotic DNA: shorter, circular, not associated with histones, doesn’t have areas areas of non-coding DNA (loose in cytoplasm)
how are eukaryotic chromosomes structured in eukaryotic cells?
through supercoiling
what is the process of supercoiling?
- DNA = wrapped around histones, forming chromatin
- histones associate in groups of 8 to form nucleosomes (beads on a string)
- nucleosomes wrap around one another forming a solenoid fibre (tightly coiled structure)
- solenoid fibres wrap around scaffolding proteins
- solenoid itself is further coiled to save space -> supercoiling (makes up chromosomes as a whole)
what are the features of DNA that mitochondria and chloroplasts both contain?
circular DNA, no areas of non-coding DNA, not associated w proteins
what is the endosymbiont theory?
states that some of the organelles in eukaryotic cells were once prokaryotic microbes
(larger cell engulfed mitochondria/chloroplast by endocytosis and remained inside the host cell being able to replicate instead of being digested)
what is a gene?
a sequence of DNA which codes for a polypeptide / functional RNA
(present at a specific locus in the DNA molecule) s
what is the genetic code of an organism?
the sequence of bases along its DNA
contains thousands of genes/cistrons (each codes for a specific polypeptide)
what are the natures of the genetic code?
- universal
- degenerate
- non-overlapping
how is the genetic code universal?
the same sequences of bases codes for the same amino acids in all organisms
how is the genetic code degenerate?
each amino acid is coded for than more than one triplet
(triplet code because 20 amino acids
4 bases
4^3 produced 64 combination, adequate for 20 amino acids)
how is the genetic code non-overlapping?
each base is only part of one codon, and each codon codes for one amino acid
what is protein synthesis?
production of a chain of amino acids and forms a primary structure of a protein
what are the stages of protein synthesis? (brief)
- TRANSCRIPTION of gene in the NUCLEUS - mRNA is formed
- processing of mRNA
- TRANSLATION of mRNA in a RIBOSOME - a polypeptide chain is formed
- MODIFICATION of the protein
what is RNA and what is its structure?
RNA = polymer made up of repeating mononucleotide sub-units
forms a single strand where each nucleotide is made up of
- pentose sugar ribose
- one organic base ( AGUC)
- phosphate group
what are the characteristics of mRNA (messenger RNA)?
mRNA = a copy of a gene from DNA
created in the nucleus and then leaves the nucleus to carry the copy of the genetic code of one gene to a ribosome in the cytoplasm
mRNA =
short : (length of one gene so it can leave the nucleus)
short-lived : (temporarily help create protein and can carry out function before enzymes break it down)
single-stranded with codons (3 bases coding for a specific amino acid)