Protein Synthesis: Gene Expression & Nucleic Acids

Protein Synthesis

Central Dogma & Mutations

What you need to understand for this unit.

●Describe the process in which genes are expressed.

●Explain the process of protein synthesis.

●Show how changes in the genetic code impact an organism.

Gene Expression

Cell Differentiation

Remember that cells in your body come in all
shapes and sizes but they all have the same
exact genetic code.

All somatic cells in an organism have identical
DNA.

Genes that are turned on are ‘expressed’.

‘Expressed’ means those pieces of DNA are
being used to make proteins that drive the
structure and function of that cell.

Cell shape and function is determined by which
genes in the DNA are activated, or expressed.

Vocab Help
Gene = a section of DNA that codes for a protein

Multiple Choice

Cellular differentiation is a process that changes a less specialized cell into a more specialized cell.

Which of the following controls the process of cell differentiation?

• RNA coding ribosomes.

• Cell division caused by mitosis.

• Genetic information stored in DNA.

• Mitochondria in cell cytoplasm.

Gene Expression

The central dogma of biology is gene
expression.

Only certain genes are ‘on’ in a cell
at certain times.

When genes are ‘on’ they are being
transcribed then translated.

This means the protein they code for
is being produced.

Gene expression is protein synthesis.

Central Dogma of Biology

Within living organisms proteins are coded for by
DNA.

1.

DNA is transcribed into RNA.

2.

RNA is translated into Proteins.

Protein Synthesis

DNA → RNA → Protein

Vocab Help
Transcribe = To Copy
Translate = To Decode

Multiple Choice

Which of the following statements best supports the theory that gene expression is a regulated process?

• Genes produce mutations regularly.

• Gene expression occurs only during cell growth.

• Some genes are inactive or not expressed.

• The location of alleles determines gene expression.

Nucleic Acids

Nucleic Acid

Monomer = nucleotides

Forms a helix

The Phosphate(P) and Sugar (CHO) form a backbone.

The Nitrogen bases (A, T, U, C, G) create a sequence.

DNA is a double helix, RNA is a single stranded helix

Polymer that creates genetic code, commonly known as DNA and RNA.

Nucleotide

The subunit, or building block, of a nucleic acid.

Nucleotide

Sugar-Phosphate
Backbone

Nitrogen base-pairs

Nitrogen Bases

Molecules that create the code (steps/rungs of the ladder) in a nucleic acid.

There are 5 nitrogen bases:

-(A) Adenine

-(T) Thymine (DNA)

-(U) Uracil (RNA)

-(G) Guanine

-(C) Cytosine

Nucleotides are named after what their
nitrogen base is.

DNA vs RNA

DNA

RNA

-Deoxyribonucleic Acid

-Sugar Deoxyribose

-Double Stranded

-A, T, G, C

-In Eukaryotes, remains in nucleus

-Stores genetic information

-Ribonucleic Acid

-Sugar Ribose

-Single Stranded

-A, U, G, C

-In the nucleus (nucleolus),
cytoplasm & Rough ER

-Transmits genetic information

Copy this table in your notes.

DNA (Deoxyribonucleic Acid)

Deoxyribose Sugar

Nitrogen Bases (A, T, C & G) make the
genetic code.

Is a double stranded, two chains
bonded together.

Contains the entire genetic code of
the organism.

DNA Bonds

Hydrogen bonds form between
the complementary base pairs.

A ←→ T

Apple Trees

G ←→ C Green Caterpillars

Vocab Help
Complementary = work well together

Multiple Choice

Nucleotides in the strands of DNA molecules are held together by -

• hydrogen bonds
• ionic bonds
• covalent bonds

• phosphodiester bonds

RNA (Ribonucleic Acid)

Ribose Sugar

Nitrogen Bases are A, U, C, G.

A single stranded spiral molecule.

A copy of a specific gene coded for
in the DNA.

Multiple Choice

How is the information for specifying the traits of an organism carried in the structure of the DNA?

• Traits are coded for by deoxyribose sugars.

• The sequence of nucleotides in DNA carries the information for specifying the traits of an organism.
• The number of chromosomes in an organism defines its traits.
• The shape of an organism's cells carries the information for its traits.

RNA (Ribonucleic Acid)

3 Types of RNA

mRNA: messenger RNA

A copy of the DNA gene.

rRNA: ribosomal RNA

Makes up part of the ribosome.

tRNA: transfer RNA

Brings in the amino acid coded
for by the mRNA.

Complementary Base-Pairs

In a nucleic acid, nitrogen bases pair up in a specific way, complementary.

Nitrogen bases: Adenosine (A), Thymine (T), Uracil (U), Cytosine (C), and Guanine (G)

DNA

A ←→ T
C ←→ G

RNA

A → U and T → A
C ←→ G

Vocab Help
Complementary Base-Pairs = Nitrogen bases that pair and create codes for proteins in genetic material.

Multiple Choice

Look at the cellular process shown.

Which molecule delivers amino acids to the ribosome during this cellular process?

• mRNA
• DNA
• tRNA
• ribosomal protein

Multiple Choice

Eye color, hair color, and height are all traits that are expressed in humans. Which of the following best describes how these traits are determined?

• These traits are determined by lifestyle choices.
• These traits are determined by diet and nutrition.
• These traits are determined by genetic inheritance.
• These traits are determined by environmental factors.

Multiple Choice

Bacteria can be genetically modified to produce human insulin for the medical treatment of diabetic patients.  The human insulin gene is placed into the DNA of a bacterium through the use of restriction enzymes and the bacterium becomes an insulin-producing factory.

This is evidence that bacteria and humans -

• are completely different organisms with no genetic overlap.
• cannot be modified for human use due to ethical concerns.
• produce only animal proteins and not human proteins.
• share genetic similarities that allow for gene transfer.