Biology Exam - (RNA, RNA, and Proteins)

Moleculer Biology covering (DNA, RNA, and Proteins)

DNA - what is the structure and function

______ is a molecule that stores the genetic instructions an organism needs for growth, repair, reproduction, and making proteins.

• _____ stands for deoxyribonucleic acid.

• It is found mainly in the nucleus.

• Its shape is a double helix, which looks like a twisted ladder.

• ______ controls inherited traits by giving instructions for protein production.

Nucleotides

_________ are the small repeating units that join together to make up a DNA strand.

• Each ________ has three parts: a sugar, a phosphate group, and a nitrogen base.

• DNA is made from many ________ linked together.

• The order of the _________ forms the genetic code.

deoxyribose

__________ is the five-carbon sugar found in DNA nucleotides.

• It is part of the backbone of DNA.

• It joins with phosphate groups to form the sides of the DNA ladder.

• RNA has ribose instead, not __________.

purines

________ are the larger nitrogen bases in DNA, and they include adenine and guanine.

• Adenine (A) and guanine (G) are _______.

• _______ always pair with pyrimidines.

• This helps keep the DNA molecule the same width.

pyrimidines

____________ are the smaller nitrogen bases in DNA, and they include thymine and cytosine.

• Thymine (T) and cytosine (C) are ___________.

• _________ pair with purines in DNA.

• This pairing keeps the DNA structure balanced.

complementary bases

_____________________ are the specific base pairs in DNA that always match in the same way.

• Adenine pairs with thymine.

• Cytosine pairs with guanine.

• These pairing rules are important for DNA replication and protein synthesis.

 anti-parallel

______________ means that the two strands of DNA run in opposite directions.

• One strand runs one way and the other runs the opposite way.

• This arrangement helps enzymes copy DNA properly.

• It is an important part of DNA’s structure.

adenine

_________ is a nitrogen base in DNA that always pairs with thymine.

• Its symbol is A.

• It is a purine.

• In RNA, adenine pairs with uracil instead of thymine.

thymine

_____________ is a nitrogen base in DNA that always pairs with adenine.

• Its symbol is T.

• It is a pyrimidine.

• ___________ is found in DNA, but not in RNA.

cytosine

_____________ is a nitrogen base in DNA that always pairs with guanine.

• Its symbol is C.

• It is a pyrimidine.

• It follows the complementary base-pairing rule.

guanine

_____________ is a nitrogen base in DNA that always pairs with cytosine.

• Its symbol is G.

• It is a purine.

• It helps complete one of the DNA base pairs.

DNA Replication – steps and enzymes involved

_____________ is the process where DNA makes an exact copy of itself before the cell divides.

• This happens before mitosis or meiosis.

• It makes sure each new cell gets the same genetic information.

• The process uses enzymes to unzip and rebuild DNA.

Semi-conservative

_____________ replication means that each new DNA molecule contains one original strand and one newly made strand.

• Half of the original DNA is kept in each new copy.

• This helps preserve genetic information accurately.

• It is the accepted model of DNA replication.

parent strand

_____________ is one of the original DNA strands that serves as a template during replication.

• The old strand guides the building of the new strand.

• New nucleotides are added based on complementary base pairing.

• Each _____________ becomes part of a new DNA molecule.

lagging strand

The _____________ is the new DNA strand that is built in short pieces during replication.

• It is made in sections because it runs in the opposite direction.

• These short pieces are called Okazaki fragments.

• The fragments must later be joined together.

leading strand

_____________ is the new DNA strand that is built continuously during replication.

• It is made in one smooth direction.

• DNA polymerase can follow the replication fork easily on this strand.

• It does not need to be built in fragments.

helicase

_____________ is the enzyme that unwinds and unzips the DNA double helix at the start of replication.

• It breaks the hydrogen bonds between base pairs.

• This separates the two DNA strands.

• It creates the replication fork.

primers

_____________ are short RNA sequences that give DNA polymerase a place to start building a new DNA strand.

• DNA polymerase cannot start on its own.

• _____________ are laid down before new DNA nucleotides are added.

• They are later replaced with DNA.

primase

• _____________ is the enzyme that makes the RNA primers needed for DNA replication.

• It adds the short starter sequence.

• This allows DNA polymerase to begin copying the DNA.

• It works on both the leading and lagging strands.

DNA polymerase

• _____________ is the enzyme that adds new DNA nucleotides to the growing strand during replication.

• It matches bases using complementary base-pairing rules.

• It builds the new strand in the correct order.

• It also helps proofread for mistakes in some cases.

Ligase

• _____________ is the enzyme that joins DNA fragments together by sealing the sugar-phosphate backbone.

• It is especially important on the lagging strand.

• It connects the Okazaki fragments into one continuous strand.

• It acts like a glue for DNA.

SSSBs (Single-strand binding proteins)

• _____________, or _____________, are proteins that keep the separated DNA strands from joining back together during replication.

• They stabilize the open DNA strands.

• They help keep the replication process organized.

• Without them, the strands could reattach too soon.

Okazaki fragments

• _____________ are the short pieces of DNA that are formed on the lagging strand during replication.

• They are made because the lagging strand is copied in sections.

• Each fragment starts with a primer.

• Ligase later joins them together.

 RNA – structure, types, function

• _____________ is a nucleic acid that helps carry and use genetic information to make proteins.

• _____________ stands for ribonucleic acid.

• It is usually single-stranded.

• It contains ribose sugar.

• It uses uracil instead of thymine.

structure types, function

mRNA

• _____________, or _____________, is the type of RNA that carries genetic instructions from DNA to the ribosome.

• It is made during transcription.

• It contains codons that tell the order of amino acids.

• It acts like a message copied from DNA.

tRNA

• _____________, or _____________, is the type of RNA that brings amino acids to the ribosome during translation.

• Each_____________ has an anticodon.

• The anticodon matches with a codon on mRNA.

• This helps place the correct amino acid in the growing protein.

rRNA

• _____________, or _____________, is the type of RNA that makes up part of the ribosome and helps with protein synthesis.

• It helps hold mRNA and tRNA in place.

• It is part of the structure of the ribosome.

• It also helps form peptide bonds between amino acids.

ribose sugar

• _____________ is the five-carbon sugar found in RNA.

• It is different from deoxyribose in DNA.

• _____________ is part of the backbone of RNA.

• It helps make RNA chemically different from DNA.

single helix

A _____________ means that RNA usually has only one strand instead of the double-stranded structure of DNA.

• RNA is not shaped like a twisted ladder.

• Because it is _____________, it can move more easily in the cell.

• This makes it useful in protein synthesis.

uracil

• _____________ is the nitrogen base in RNA that replaces thymine and pairs with adenine.

• Its symbol is U.

• In RNA, A pairs with U.

• _____________ is only found in RNA, not DNA.

codon

A _____________is a group of three bases on mRNA that codes for one amino acid or a stop signal.

• Codons are read during translation.

• Each codon has a specific meaning on the codon chart.

• For example, some codons signal start or stop.

anticodon

An_____________ is a group of three bases on tRNA that pairs with a codon on mRNA.

• The _____________ makes sure the right amino acid is brought in.

• It is complementary to the mRNA codon.

• This helps build the correct protein sequence.

Protein Synthesis – steps of transcription and translation, using codon chart

• _____________ is the process cells use to make proteins based on the instructions in DNA.

• It has two main stages: transcription and translation.

• It turns genetic information into a working protein.

• Proteins are important for traits, enzymes, and cell functions.

Transcription

• _____________ is the process where a section of DNA is copied into mRNA in the nucleus.

• RNA polymerase attaches to DNA.

• It reads one DNA strand as a template.

• It builds a complementary mRNA strand.

introns

• _____________ are sections of RNA that are removed before the mRNA leaves the nucleus.

• Introns do not code for amino acids.

• They are cut out during RNA processing.

• They are not used in the final protein message.

exons

• _____________ are the sections of RNA that remain after introns are removed and are used to code for proteins.

• _____________ stay in the final mRNA molecule.

• They contain the instructions for amino acid order.

• They are joined together before translation.

poly-A tail

The _____________ is a string of adenine bases added to the end of mRNA after transcription.

• It helps protect the mRNA from breaking down.

• It helps the mRNA leave the nucleus.

• It also helps the ribosome recognize the mRNA.

translation

• _____________ is the process where the ribosome reads mRNA and builds a protein from amino acids.

• It happens at the ribosome in the cytoplasm.

• tRNA brings amino acids in the correct order.

• The ribosome links them together to form a protein.

ribosome

A _____________ is the cell structure where translation happens and proteins are made.

• It reads the codons on mRNA.

• It works with tRNA and rRNA.

• It joins amino acids together in the right sequence.

amino acids

• _____________ are the small molecules that join together to make proteins.

• They are the building blocks of proteins.

• The order of _____________ determines the protein’s shape and function.

• Each codon on mRNA codes for a specific _____________.

 polypeptide bonds

• _____________ are the chemical bonds that join amino acids together in a growing protein chain.

• These bonds form during translation.

• The ribosome helps create them.

• A chain of amino acids joined by peptide bonds is called a _____________.

RNA polymerase

• _____________ is the enzyme that builds mRNA during transcription by using DNA as a template.

• It attaches to a gene on the DNA.

• It reads the DNA sequence.

• It puts together a complementary RNA strand.

Using a codon chart

A _____________ is used to match each mRNA codon to its correct amino acid during translation.

• You read the mRNA codon, not the DNA strand.

• Every 3 bases gives one amino acid.

• Some codons are start codons and some are stop codons.

Gene mutations – define and identify different types

A _____________ is a change in the DNA base sequence of a gene.

• Mutations can happen during replication or because of outside factors.

• Some mutations have no effect, while others can change proteins.

• Mutations can be small or large.

Point mutation

A_____________ is a mutation that affects only one nucleotide or one base pair in the DNA sequence.

• It usually involves a substitution.

• It changes only one position in the code.

• It may or may not affect the protein.

 neutral mutation

A _____________is a mutation that does not significantly affect the function of the protein.

• The protein may still work normally.

• Sometimes the amino acid change does not matter much.

• _____________ do not usually cause noticeable effects.

silent mutation

A _____________ is a mutation where the DNA base changes but the amino acid stays the same.

• This happens because some amino acids are coded for by more than one codon.

• The protein does not change.

• It is usually harmless.

missense mutation

A _____________ is a mutation where one base changes and causes a different amino acid to be placed in the protein.

• This can change the protein’s shape or function.

• Some _____________ have small effects, while others are serious.

• It depends on which amino acid is changed.

nonsense mutation

A _____________ is a mutation where a base change creates a stop codon too early.

• This causes translation to stop before the protein is finished.

• The protein is usually shorter than normal.

• It often makes the protein nonfunctional.

 substitution

A _____________ is a mutation where one base is replaced by another base.

• It is a type of point mutation.

• It can cause a silent, missense, or nonsense mutation.

• Only one base is switched.

Frameshift mutation

A _____________ is a mutation that changes the reading _____________ of the genetic code by adding or removing a base.

• It affects every codon after the mutation.

• It usually has a major effect on the protein.

• Insertion and deletion are the main types of _____________.

deletion

A _____________ is a mutation where one or more nucleotides are removed from the DNA sequence.

• If the number removed is not a multiple of three, it causes a frameshift.

• This can completely change the amino acid sequence after that point.

• It often causes serious protein changes.

insertion

An _____________ is a mutation where one or more nucleotides are added into the DNA sequence.

• If the number added is not a multiple of three, it causes a frameshift.

• This changes the codon grouping.

• It can greatly affect the final protein.