Central Dogma of Biology

Springfield Central High School

What are atoms, ions, elements and molecules? What makes carbon the element of life? What are the key six elements found in living things? Where can you find carbon on the periodic table? How many  electrons  can carbon share? What are single, double and triple bonds? What are the basic shapes that carbon molecules can

make? What are the four basic organic molecules for life? What is a macromolecule or a polymer? What is a subunit or monomer? What is a functional group? What are the four key organic molecules’ subunits? What are the three types of carbohydrates?  What type of reaction joins monomers into polymers? What functions can lipids perform? What key functional groups are found in amino acids? What is the function of enzymes? What is the central dogma of biology? What are the functions of nucleic acids?

Questions to Ponder From Lesson 2

Questions to AnswerDaily Problem Set Unit 3 - #3

1. Describe the basic structure (double helix, sugar/phosphate backbone, linked by complementary nucleotide pairs) of DNA, and describe its function in genetic inheritance.

2. Describe the basic process of DNA replication and how it relates to the transmission and conservation of the genetic code. 3. Explain the basic processes of transcription and translation, and how they result in the expression of genes.

4. Distinguish among the end products of replication, transcription, and translation.

Explain the Central Dogma of Biology.

• 3 entities : DNA RNA

Protein

• 3 Processes:Replication

Transcription

Translation

The Central Dogma DNA is replicated into more DNA

During S phase of a cell's life, DNA is replicated for new cells

DNA makes more DNA

DNA is transcribed into RNAThe information on the DNA is transcribed into

RNA

RNA is translated into ProteinsRNA delivers the DNA’s information to the site of

protein synthesis and the DNA’s info on the RNA is translated into protein from nucleic acid

The central dogma of biology consists of 3 entities and 3 processes.

DNA is in the group of organic molecules called nucleic acids. Nucleic Acids are macromolecules made up of subunits called nucleotides Genes are coded messages of how, when, and where to make proteins, and are

sections of a long DNA molecule. In Eukaryotic cells DNA is found in nucleus either in chromatin or in chromosomes

What do we need to know about DNA?

- Chromatin – Unraveled DNA in the nucleus

- Chromosome – DNA wrapped around protein spools in the nucleus

DNA is made up of subunits called nucleotides.

There are 4 different types of nucleotides of DNA:

Nucleotides with Adenine, (A) Nucleotides with Guanine, (G)Nucleotides with Thymine, (T)Nucleotides with Cytosine, (C)

Each nucleotide is made up of three parts A phosphate groupA deoxyribose sugarA nitrogen base, there are 4 bases,

(A,T,C,G)

DNA consists of two strands of nucleotides with sugars and phosphates on the outside and bases bonded together on the inside.

The paired strands twisted zipper shape is called a double helix.

The form of DNA is a double helix

Structure of DNA

Overview of DNA

Double Helix Structure of DNA The base adenine (A)

bonds with thymine (T) The base guanine (G)

bonds with cytosine (C). These bases are bonded

together by hydrogen bonds.

This is known as complementary base pairing!

Explain complimentary base pairing.

Functions of DNA DNA has two functions:

◦ 1. Hold information on how to make proteins◦ 2. Make more DNA

The main function of DNA is to store genetic information.  The information that DNA stores is how, when, and where to make

proteins. • Genes are sections of DNA that have the

information for how to build one protein.   • DNA is the molecule of heredity.

The second function of DNA is simply to make more DNA; this is called replication.

DNA replication is the process of DNA making more DNA.◦ Replication begins when an enzyme binds to the DNA. ◦ The enzyme (Helicase) separates the joined base pairs (or unzips the

double helix).◦ As the nucleotides separate another enzyme (DNA polymerase)

binds to the separated chains and begins to assemble free nucleotides into new double helixes. 

Replication of DNA View this DNA Synthesis Animation

Here’s an animation on bacterial DNA replication

Moving along

Transcription - DNA is transcribed into RNA

In mRNA, a three nucleotide sequence is known as a codon. Each codon identifies a particular amino acid.

The amino acid order is determined by the order of codons.

The amino acid order also determined the protein’s shape (form).

A protein’s shape allows it to carry out a specific function

There are three types of RNA ◦ Messenger RNA (mRNA) - is a strand of nucleic acid with the

DNA's information on the order of amino acids for a certain protein encoded on it.

◦ Transfer RNA (tRNA) – “Translator” – in the translation process, converts nucleic acid codes to amino acid.

◦ Ribosomal RNA (rRNA) – “Protein Factory” – translation occurs here. Contain binding sites for tRNA and mRNA.

Structure and Function of Ribonucleic Acid (RNA)

mRNA

rRNAtRNA

Ribonucleic Acid and the transcription of DNA to RNA In the nucleus a second type of

nucleic acid is made based on the order of nucleotides making up the codons and genes: RNA

Messenger RNA (mRNA) is a type of nucleic acid

The process of copying DNA’s information into mRNA is called transcription.

The job of mRNA is to deliver the DNA’s information to the cytoplasm where proteins are made.

mRNA mRNA is made up of subunits called nucleotides. There are 4 different types of nucleotides of RNA:

◦ Nucleotides with Adenine, (A) ◦ Nucleotides with Guanine, (G)◦ Nucleotides with Uracil, (U)◦ Nucleotides with Cytosine, (C)

Each nucleotide is made up of three parts ◦ A phosphate group◦ A ribose sugar◦ A nitrogen base, there are 4 bases, (A,U,C,G)

In mRNA, a three nucleotide sequence is known as a codon. Each codon identifies a particular amino acid.

The amino acid order is determined by the order of codons.

The amino acid order also determined the protein’s shape (form).

A protein’s shape allows it to carry out a specific function

Codons can make the same amino acid

Transcription is the process of making RNA from a DNA template. Transcription of RNA occurs in the nucleus There are three stages to Transcription:

◦ Initiation – an enzyme (RNA Polymerase) attaches to DNA at the promoter region. The promoter region contains a start codon, methionine (AUG).

◦ Transcription – RNA synthesis begins. A (on DNA strand) will bond to U (on RNA strand). There are no T’s on RNA strands.

◦ Termination – RNA Polymerase reaches locations containing stop codons, (UAA, UAG, UGA), at this point, RNA synthesis stops. RNA polymerase and the newly synthesized mRNA detaches from the DNA. The mRNA leaves the nucleus and enters the cytoplasm

Transcription

View this Animation on Transcription of RNA

Animation of mRNA

Moving along

Transcription - DNA is transcribed into RNA

In mRNA, a three nucleotide sequence is known as a codon. Each codon identifies a particular amino acid.

The amino acid order is determined by the order of codons.

The amino acid order also determined the protein’s shape (form).

A protein’s shape allows it to carry out a specific function

The process of using the DNA’s information, now on the mRNA to produce a protein is called translation.

Translation is a process in which the order of bases in mRNA codes for the order of amino acids in a protein.

Once the mRNA has moved out of the nucleus into the cytoplasm, the process of making a protein begins.◦ Cytoplasm is filled with nutrients like amino acids

Translation View this animation on Translation

Translation The ribosome attaches to

mRNA to begin making proteins.

The ribosome require amino acids to produce proteins.

The amino acids are brought to the ribosome by transfer RNA (tRNA).

tRNA on one end contain sets of three nucleotide (anticodon) that forms base pair with the mRNA codon.

On the other end, is carried the amino acid that corresponds to the anticodon.

The amino acids are assembled one after another based on the order of nitrogen bases in the codons.

Translation stops when the ribosome encounters one of the stop codons (UAA, UAG, or UGA.)

Overview of Transcription and Translation in Eukaryotic cells

What are DNA, mRNA,and tRNA? What is the twisted shape of DNA called? What is the Central Dogma of Biology? Define entities, processes, and properties . What are the entities in the Central Dogma? What are processes in the Central Dogma? What are genes and codons? What are the four bases found on DNA nucleotides? What are the four bases found on RNA nucleotides? Which nucleotides are purines and which are pyrimidines? What enzymes are required for DNA replication? Which nucleotides are complimentary? Why can genetic information remain reasonably constant?  What happens when mutations are made? What is the function of tRNA?

Questions to Ponder From Lesson 3