CAIE Biology A-Level Flashcards - Nucleic Acids & Protein Synthesis PDF

CAIE Biology A-level Topic 6: Nucleic Acids and Protein Synthesis Flashcards PMT Education is licensed under https://bit.ly/pmt-cc This work by https://bit.ly/pmt-edu-cc CC BY-NC-ND 4.0...

CAIE Biology A-level Topic 6: Nucleic Acids and Protein Synthesis Flashcards PMT Education is licensed under https://bit.ly/pmt-cc This work by https://bit.ly/pmt-edu-cc CC BY-NC-ND 4.0 https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Draw the structure of a nucleotide. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Draw the structure of a nucleotide. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Name the pentose sugars in DNA and RNA. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Name the pentose sugars in DNA and RNA. Deoxyribose in DNA Ribose in RNA https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Describe the structure of DNA. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Describe the structure of DNA. Double-stranded polymer of nucleotides twisted to form a double helix Nucleotides joined by phosphodiester bonds Hydrogen bonds form between complementary base pairs, A and T, C and G Antiparallel strands https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Name the purine bases and describe their structure. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Name the purine bases and describe their structure. Adenine C5H5N5 Guanine C5H5N5O two-ring molecules https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Name the pyrimidine bases and describe their structure. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Name the pyrimidine bases and describe their structure. one-ring molecules Thymine C5H6N2O2 Cytosine C4H5N3O Uracil C4H4N2O2 https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What is complementary base pairing? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What is complementary base pairing? Describes how hydrogen bonds form between complementary purine and pyrimidine bases Two bonds form between A and T (or U) Three bonds form between G and C https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Why is DNA replication described as semiconservative? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Why is DNA replication described as semiconservative? Strands from original DNA molecule act as templates New DNA molecule contains 1 old strand and 1 new strand (specific base pairing enables genetic material to be conserved accurately) https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc How is a new strand formed during semiconservative replication? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc How is a new strand formed during semiconservative replication? 1. Free nucleotides from nuclear sap attach to exposed bases via complementary base pairing 2. DNA polymerase joins adjacent nucleotides on new strand in a 5’ → 3’ direction via condensation reactions to form phosphodiester bonds 3. Hydrogen bonds form between complementary base pairs https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Outline the role of DNA ligase in DNA replication. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Outline the role of DNA ligase in DNA replication. As DNA replicates in an antiparallel fashion, the leading strand (5’ 3’) is replicated continuously whereas the lagging end (3’ 5’) is replicated discontinuously. Short nucleotide sequences (Okazaki fragments) are formed. DNA ligase catalyses the formation of phosphodiester bonds between Okazaki fragments. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Describe the structure of RNA. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Describe the structure of RNA. Single-stranded polymer of nucleotides Nucleotides joined by phosphodiester bonds Hydrogen bonds form between complementary base pairs, A and U, C and G https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What is the function of mRNA? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What is the function of mRNA? Carries genetic information from the nucleus to the ribosomes for protein synthesis. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc How do genes determine the structure of proteins? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc How do genes determine the structure of proteins? DNA base triplets code for amino acids Triplet sequence determines amino acid sequence Sequence of amino acids determines protein’s primary structure Protein primary structure determines where bonds form when folding into tertiary structure, e.g. determines shape of enzyme active site https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What is a mutation? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What is a mutation? A random alteration to the DNA base sequence, altering the order of coded amino acids. This may result in a change in protein structure. Mutations often arise spontaneously during DNA replication. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc State the three types of gene mutation. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc State the three types of gene mutation. Substitution Insertion Deletion https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What are the consequences of substitution mutations? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What are the consequences of substitution mutations? Silent mutation (no consequence) as DNA is degenerate Mutation may alter the amino acid coded for. This can alter the structure of the polypeptide causing it to no longer function - missense mutation Mutation may lead to the production of a stop codon. The length of the polypeptide chain is shorter - nonsense mutation https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What are the consequences of insertion/ deletion mutations? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What are the consequences of insertion/ deletion mutations? Produce a frameshift, altering each subsequent codon and rendering the protein non-functional. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Describe the structure of tRNA. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Describe the structure of tRNA. Single strand of 80 nucleotides Folded into clover shape (some paired bases) Anticodon on one end, amino acid binding site on the other ○ Anticodon binds to complementary mRNA codon ○ Amino acid corresponds to anticodon https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What do transcription and translation produce and where do they occur? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What do transcription and translation produce and where do they occur? Transcription produces mRNA, occurs in nucleus. Translation produces proteins, occurs in the cytoplasm in ribosomes (made of protein and rRNA). https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Outline the process of transcription. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Outline the process of transcription. 1. DNA helicase unwinds section of DNA, breaking hydrogen bonds between the DNA strands. Antisense strand acts as a template. 2. RNA polymerase binds to promoter region on a gene 3. Free RNA nucleotides align next to their complementary bases 4. RNA polymerase joins adjacent RNA nucleotides, forming phosphodiester bonds 5. RNA polymerase reaches stop codon and detaches. mRNA complete. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Define the term exon. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Define the term exon. Regions of DNA or RNA that code for amino acid sequences. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Define the term intron. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Define the term intron. Non-coding sequences of DNA found between exons. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What happens after a strand of mRNA is transcribed? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What happens after a strand of mRNA is transcribed? RNA polymerase detaches at terminator region Hydrogen bonds reform and DNA rewinds Splicing removes introns from pre-mRNA (primary transcript) in eukaryotic cells, leaving only exons mRNA moves out of nucleus via nuclear pore and attaches to ribosome https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Outline the process of translation. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Outline the process of translation. 1. mRNA attaches to groove between subunits of ribosome 2. Ribosome moves along mRNA until ‘start’ codon reached 3. Amino acid-tRNA complex anticodon attaches to complementary mRNA codon via hydrogen bonding. Another complex binds 4. Peptide bond forms between adjacent amino acids in the complexes 5. Ribosome moves along one codon and release empty tRNA. Process continues to form polypeptide chain until ‘stop’ codon is reached. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc