AGN001 Flashcards by Alona Casilao

is the process by which the instructions in DNA are converted into a functional product.

“Central Dogma”

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What year is the central dogma proposed, and who discovered it?

1958 by Francis Crick

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The central dogma of molecular biology explains what?

*the flow of genetic information ( from DNA to RNA)
* to make a functional product, a protein.

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contains the information needed to make all of our proteins

DNA

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It is a messenger that carries this information to the ribosomes

RNA

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serve as factories in the cell where the information is ‘translated’ from a code into
the functional product.

Ribosomes

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The process by which the DNA instructions are converted into the functional product is called _______________.

gene expression

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Give the two key stages of gene expression

transcription and translation

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During this stage the information in the DNA of every cell is converted into small, portable RNA messages.

Transcription

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During this stage, the messages travel from where the DNA is in the cell nucleus to the ribosomes where they are ‘read’ to make specific proteins.

translation

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The central dogma states that the pattern of information that occurs most frequently in our cells
is:

o From existing DNA to make new DNA (DNA Replication)

o From DNA to make new RNA (transcription)

o From RNA to make new proteins (translation)

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It is the process by which DNA makes a copy of itself during cell division.

DNA replication

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what is the first step in DNA replication?

to ‘unzip’ the double helix structure of the DNA molecule.

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an enzyme which breaks the hydrogen bonds holding the complementary bases of DNA together (A with T, C with G).

helicase

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separation of the two single strands of DNA creates what shape?

“Y”

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what is the “Y” shape created from separation of two single strands of DNA called?

replication ‘fork’

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the strands that is oriented in the 3’ to 5’ direction (towards the replication fork).

leading strand

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the strand that is oriented in the 5’ to 3’ direction (away from the replication fork).

lagging strand

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short piece of RNA (produced by an enzyme called primase) comes along and binds to the end of the leading strand.

a primer

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acts as the starting point for DNA synthesis.

primer

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Leading strand replication is called ___________.

continuous.

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Chunks of DNA that are then added to the lagging strand also in the 5’ to 3’ direction.

Okazaki fragments,

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This type of replication is called discontinuous.

Lagging strand

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It is an enzyme that strips away the primer(s) once all of the bases are matched up (A with T, C with G)

exonuclease

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The new strand is _________ to make sure there are no mistakes in the new DNA sequence.

proofread

an enzyme that seals up the sequence of DNA into two continuous double strands.

DNA ligase

DNA replication is described as _____________, half of the chain is part of the original DNA molecule, half is brand new.

semi-conservative

It is the first step in gene expression. It involves copying a gene's DNA sequence to make an RNA molecule.

Transcription

Transcription is performed by these enzymes , it links nucleotides to form an RNA strand (using a DNA strand as a template).

RNA polymerases,

Give the three stages of Transcription:

initiation elongation termination

Transcription is controlled _________ for each gene in your genome.

separately

In eukaryotes, RNA molecules must be processed after transcription:

they are spliced and have a 5' cap and poly-A tail put on their ends.

which information is used to construct a functional product such as a protein?

gene

what is the goal of transcription?

to make a RNA copy of a gene's DNA sequence.

For a protein-coding gene, the RNA copy, or transcript, carries the information needed to build a ______________________.

polypeptide (protein or protein subunit).

they need to go through some processing steps before translation into proteins.

Eukaryotic transcripts

It is the main enzyme involved in transcription, which uses a single-stranded DNA template to synthesize a complementary strand of RNA.

RNA polymerase

It builds an RNA strand in the 5' to 3' direction, adding each new nucleotide to the 3' end of the strand.

RNA polymerase

Stage of transcription where RNA polymerase binds to a sequence of DNA called the promoter, found near the beginning of a gene.

Initiation

In initiation stage of transcription, each gene (or group of co-transcribed genes, in bacteria) has its own ______________.

promoter

In the Elongation step of transcription, what is the One strand of DNA that acts as a template for RNA polymerase?

template strand

The RNA transcript carries the same information as the non-template (coding) strand of DNA, but it contains the base____________ instead of thymine (T).

Uracil (U)

What allows the DNA to close back up and form a double helix?

dangling string

In the termination step of transcription, what are the sequences that signals the RNA transcript is complete?

terminators

It encodes a region of RNA that forms a hairpin structure followed by a string of U nucleotides.

terminator DNA

It is a structure in the transcript that causes the RNA polymerase to stall.

hairpin structure

These come after the hairpin forms weak bonds with the A nucleotides of the DNA template, allowing the transcript to separate from the template and ending transcription.

U nucleotides

In bacteria, RNA transcripts can act as?

messenger RNAs (mRNAs)

In eukaryotes, the transcript of a protein-coding gene is called a___________ and must go through extra processing before it can direct translation.

pre-mRNA

Eukaryotic pre-mRNAs must have their ends modified, by addition of a_______ (at the beginning) and__________ (at the end).

5' cap (at the beginning) 3' poly-A tail (at the end)

Many eukaryotic pre-mRNAs undergo ________.

splicing

During splicing process, it is the parts of the pre-mRNA that are chopped out.

introns

During splicing process, it is the remaining pieces that are stuck back together.

exons

_______________ increase the stability of the mRNA.

End modifications

It gives the mRNA its correct sequence.

splicing

In this stage, the mRNA is "decoded" to build a protein (or a chunk/subunit of a protein) that contains a specific series of amino acids.

Translation

During translation, a cell “reads” the information in a messenger RNA (mRNA) and uses it to build a________.

protein.

mRNA does not always encode—provide instructions for—a whole protein. Instead, it always encodes a___________, or chain of amino acids.

polypeptide

Chain of amino acid is called

polypeptide

How many codons are there for amino acids?

61 codons

In an mRNA, the instructions for building a polypeptide are RNA nucleotides (As, Us, Cs, and Gs) read in groups of three. These groups of three are called ________.

codons

This codon specifies the amino acid methionine and also acts as a start codon to signal the start of protein construction.

AUG

stop codons

UAA UAG UGA

Is the collection of codon-amino acid relationships.

genetic code

Methionine

AUG

Threonine

ACG

Glutamate

GAG

Leucine

CUU

CGG

Arginine

AGC

Serine

Two types of molecules with key roles in translation.

tRNAs and ribosomes.

are molecular "bridges" that connect mRNA codons to the amino acids they encode.

Transfer RNAs, or tRNAs

One end of each tRNA has a sequence of three nucleotides, which can bind to specific mRNA codons.

anticodon

are composed of a small and large subunit and have three sites where tRNAs can bind to an mRNA (the A, P, and E sites).

Ribosomes

the structures where polypeptides (proteins) are built.

Ribosomes

Ribosomes are made up of ___________ and ________________.

protein and RNA (ribosomal RNA, or rRNA).

How many subunits do ribosomes have?

Two subunit

It acts as an enzyme, catalyzing the chemical reaction that links amino acids together to make a chain.

Ribosome

Steps of Translation

* The cells are making new proteins every second of the day. And each of those proteins must contain the right set of amino acids, linked together in just the right order. * Translation can be divided into three stages: initiation (starting off), elongation (adding on to the protein chain), and termination (finishing up)