3.4.2 DNA and protein synthesis Flashcards
Describe the process of transcription in protein synthesis
- By action of DNA helicase hydrogen bonds between bases are broken
- One strand of the DNA acts as a template strand as contains the desired gene in DNA strand
- Free RNA nucleotides align by complementary base parings
- In RNA Uracil base pairs with adenine on DNA
- RNA polymerase joins nucleotides forming phosphodiester bonds
- Pre - mRNA is then spliced removing introns forming mRNA
What happens during splicing of pre mRNA ?
Introns are removed
Describe the process of translation in protein synthesis
- mRNA attaches to a ribosome
- Ribosome moves to / finds the start codon
- tRNA anticodons bind to complementary mRNA codons
- tRNA brings a specific amino acid
- Amino acids join by peptide bonds
- Amino acids join together with the use of ATP
- tRNA released after amino acid joined to polypeptide
- The ribosome moves along the mRNA to next two codons to form the polypeptide chain
Give the 4 differences between mRNA and tRNA
mRNA - linear, tRNA - clover leaf shape
mRNA - no amino acid binding site, tRNA - amino acid binding site
mRNA - longer, more nucleotides, tRNA - shorter, less nucleotides
mRNA - codon, tRNA - anticodon
Give 4 differences between DNA and RNA
DNA - double stranded, RNA - single stranded
DNA - thymine, RNA - uracil
DNA - deoxyribose, RNA - ribose
DNA - long, RNA - short
Describe how ATP is resynthesises in cells
From ADP and Pi
By ATP synthase
During respiration/photosynthesis
Give two ways in which hydrolysis of ATP is used in cells
Provide energy
To add phosphate to other substances and make them more reactive
In a eukaryotic cell, transcription results in a molecule of pre mRNA that is modified to produce mRNA. In a prokaryotic cell transcription produces mRNA directly. Explain the difference
DNA of eukaryotic cell has non coding regions (introns)
These are removed after transcription
Describe how the production of messenger RNA in a eukaryotic cell in different from the production of mRNA is a prokaryotic cell
Pre mRNA is only produced in eukaryote cell
Splicing only occurs in eukaryote
Introns removed in eukaryote, introns not present in prokaryotes
Aspartic acid and proline are both amino acids. Describe how two amino acids differ
from one another. You may use a diagram to help your description.
Different R groups
During replication, the two DNA strands separate and each acts as a template for the production of a new strand. As anew strand of DNA is produced, nucleotides can only be added in the 5’ to 3’ direction. Explain why this is the case using your knowledge on DNA replication and enzyme action.
DNA polymerase is an enzyme which has a specific shape so can therefore only bind to the 5’ end of the strand as the shape at the 3’ to 5’ is different so not complementary
Why does DNA polymerase work in one direction and go other opposite in the other
DNA has an antiparallel structure this means that the nucleotides are arranged in a different order. DNA polymerase is an enzyme with a specific shape and is only complementary to the 5’ to 3’ direction
