Protein Synthesis (Unit 6 - Part 2) Flashcards
what happens to DNA in a cell?
DNA replication and protein synthesis
DNA replication
DNA is replicated to prepare for cell division (mitosis)
protein synthesis
its code (sequence of nucleotides) can be read to make proteins
materials needed for DNA replication
-original DNA which acts as a template
-free nucleotides (building blocks to make the new DNA molecule)
-enzymes
1st step of DNA replication
-the DNA molecule untwists and unzips (breaking hydrogen bonds) into 2 sides
-each side serves as a template to produce new strands
2nd step of DNA replication
the free nucleotides pair up (complementary base pairs), creating 2 strands
3rd step of DNA replication
each new DNA molecule then rezips (making hydrogen bonds) and retwists
end result of DNA replication
*2 identical DNA molecules
-each molecule contains 1 original strand and 1 new strand
gene
a section of DNA that codes for a specific proteins
steps to protein synthesis
transcription and translation
transcription
*DNA to RNA
-makes an RNA copy of the DNA message
-occurs in the cells nucleus
1st step of transcription
DNA acts as a template for building mRNA
2nd step of transcription
the DNA untwists and unzips (hydrogen bonds break)
3rd step of transcription
RNA nucleotides pair up complementary to one side of the unzipped DNA molecule
4th step of transcription
the newly made mRNA moves away from the DNA-the mRNA moves out of the nucleus and goes into the cytoplasm to a ribosome
5th step of transcription
the DNA rezips and retwists and can be used again
translation
*RNA to protein
-uses mRNA instructions to build a protein from amino acids
1st step of translation
the mRNA attaches to a ribosome in the cytoplasm
2nd step of translation
mRNA is read by a ribosome in 3 base segments called codon
3rd step of translation
transfer RNA (tRNA) molecules in the cytoplasm pickup and transfer amino acids
4th step of translation
a tRNA matches up with a codon on mRNA and the tRNA drops off its amino acid
5th step of translation
a bond is formed between amino acids
6th step of translation
eventually, a stop codon is reached and the final protein is made
codon
a sequence of 3 DNA or RNA nucleotides that corresponds with a specific amino acid or stop signal during protein synthesis
when a amino acid chain is put together we get ___
protein
mutations
any change that occurs to the genetic material (DNA) of an organism
chromosomal mutation
*changes to the number of chromosomes
-a chromosomal mutation is caused when chromosomes do not separate properly during meiosis
-this creates egg or sperm cells with more or less than 23 chromosomes which then leads to a zygote with more or less than 46 chromosomes
Gene mutations
changes the order of nucleotides in the DNA and it could change the amino acid that is coded for which then may change the protein that is made
substitution
a single nucleotide is replaced by a different nucleotide
deletion
a single nucleotide is removed from the DNA sequence
insertion
a single nucleotide is added to the DNA sequence
mutagen
substances that cause mutations
why do mutations matter?
-when they form damaged proteins
-when they cause uncontrollable division (cancer)
-when they happen in gametes (they can be passed onto offspring)
