DNA and Polypeptide Synthesis Flashcards
Prokaryotic
Prokaryotic cells:
- no nucleus
- 1-5um
- free moving in the cytoplasm - in the nucleic region (nucleiod)
- no membrane bound organelle
- only unicellular life
- archaebacteria, eubacteria
Eukaryotic cells
- true nucleus
- 10-100um
- contained within a membrane bound nucleus
- membrane bound compartments such as nucleus and mitochondria
- yes (most multicellular life, exception of protists)
- animal, plants, protists and fungi
Prokaryotic DNA
Info:
Contains a single chromosome, circular strand of DNA with no membrane and free in the cytoplasm
- Circular DNA can supercoil and form a loop around a centra dense protein (scaffold) to form a nucleoid
- Non-chromosomal DNA = plasmids
Location: DNA is free moving in the cytoplasm, no membrane (nucleoid region)
Protein binding: circular DNA can supercoil and form loop around a central dense protein (called the scaffold) to form a nucleoid
Genomes are compact (contain little repetitive DNA and no introns)
Contains plasmids
Is circular in shape
Plasmids:
- Small rings floating separately in the cytoplasm
- Replicate independently of chromosome
- Codes for non-essential features but for those providing a selective advantage (antibiotic resistance)
Eukaryotic DNA
Info:
- DNA in a membrane bound nucleus
- Individual DNA molecules are arranged into separated chromosomes
- Introns are a large proportion of non-coding DNA
- Linear, double helix DNA shape
- DNA wrapped around histones which coil up to make chromosomes
- Non-nuclear DNA is not contained within the nucleus, includes mt DNA
Location:
Conatined within a membrane bound nucleus
Protein binding: is bound to histone proteins
Genomes: genomes contain large amounts of non-coding and repetitive DNA (including introns)
Contains plasmids: do not contain plasmids (but organelles such as the mitochondria)
Shape: linear - double helix
Non-chromosomal: Codes for coding proteins for respiration
- Mitochondrial DNA (mt DNA) is found in the respiratory organs of cells – can be used to trace maternal inheritance
- Mt DNA is very small (70nm), circular, double stranded, contains no introns, with only 37 genes (13 for respiration functions, 24 for RNA molecules)
- Each cell has 100-1000 mitochondria, and each contains 5-10 circular DNA molecules
Protein synthesis: DNA
DNA
Structure Double stranded molecule
Nitrogenous bases of adenine, thymine, cytosine and guanine
Location Inside nucleus
Small amount found in mitochondria and chloroplast
Role Chemical code (info) used in protein synthesis and responsible for transmitting inherited from one cell to another during cell division.
Protein synthesis: RNA
Single stranded molecule
Uracil replaces thymine
Small amount in nucleus large amount found in cytoplasm
Used in the process of protein synthesis.
Includes: Messenger RNA (mRNA), Transfer RNA (tRNA), ribosomal RNA (rRNA)
amino acid
Amino acid: a simple organic compound containing a carboxyl and amino group – building blocks of protein
peptide:
short chains of 2-50 amino acids
polypeptide:
linear molecules made of multiple peptides
protein
the functional unit, made up of one or more polypeptides
transcription
the process by which a complementary copy (mRNA) or a gene (DNA) is made in the nucleus
translation
the process by which mRNA sequence is converetd into a specific sequence of amino acids (carried by tRNA) in the ribosomes (changing language from nucleotides to AAs)
mRNA
messenger ribonucleic acid, single stranded nucleic acid, consisting of ribose sugar, phosphate backbone and nitrogen bases (AUGC)
tRNA
transfer ribonucleic acid, small RNA molecule that transfers specific amino acids to the ribosome during formation of polypeptides
codon
set of three nitrogen bases in mRNA