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Leaving Cert Biology Revision: DNA Profiling

DNA Profiling

Another name for this is DNA fingerprinting. It is a technique for using a person's DNA to create a distinctive band design. This can then be utilized to use DNA to distinguish between different persons.

Electrophoresis in Gel is used to create the pattern.

On a gel, DNA is separated into a pattern using an electric current. It is possible to copy even a tiny bit of DNA to produce more for testing.

Steps in making a DNA Profile

First, DNA is liberated. It is released from cells, just like in our previous experiment.

Step 2: Fragments of DNA are cut.

Certain regions of DNA are sliced by enzymes known as restriction enzymes.

This separates the DNA into strands of varying lengths. In the ATCG code, it consistently jumps between the same letters.

For example, one enzyme constantly snips at the coding GAATTC

Step 3: The bits of DNA are isolated.

On a sugar gel, the DNA is inserted into wells.

The negatively charged DNA travels from one end of the gel to the other when an electric current is run through it. In the gel, the shorter bits can travel farther than the larger ones, which are less mobile.

On the gel, this creates a pattern of bands or lines.

Step 4: A comparison of the patterns.

Because of specific sites of DNA cutting by restriction enzymes, your DNA consistently follows the same pattern. The gel is photographed so that the various DNA bands can be compared.

The only twins with the same DNA pattern are identical.

Screening for Genetics

Here, DNA is examined to see whether a certain gene or a gene that has been changed is present or absent.

Mutations or errors caused by replication can occur in genes.

Screening of adults Sickle cell anemia or cystic fibrosis.

It is possible to extract fetal screening cells from fluid or the placenta.

Molecular Couples receiving counseling who have a family history of genetic abnormalities might get tests and information to help them make decisions about starting a family.

RNA Ribonucleic acid

Because RNA has four bases—A, U, G, and C—it differs from DNA.

Rather than thymine, there is uracil. Ribonucleic acid (RNA)

The following is how the RNA bases, or nucleotides, will adhere to a DNA strand if it is.

Protein Synthesis

Proteins are made by a code found in DNA.

  • In the cytoplasm, ribosomes are where proteins are generated.

  • The cell nucleus is where DNA cannot exit.

  • The code is transported to the ribosome in the cytoplasm by RNA acting as a messenger.

  • The code from the DNA must first be copied by the RNA.

  • Since the code is being transcribed, this is known as transcription.


  • The ribosome is instructed to begin reading the code by the start codon.

  • The ribosome is informed that there is no more coding to read by the stop codon.

  • The three letters on the tRNA (transfer RNA) called anticodons correspond to the three letters on the mRNA called codons.

Detailed Structure of DNA Higher Level

  • A and G are the Purines.

  • T and C are the pyrimidines.

There is a double hydrogen bond connecting A and T.

A triple hydrogen bond connects C and G.

DNA Profiling 1

DNA profiling, also known as DNA fingerprinting, is a technique used to identify individuals based on their unique genetic makeup. It involves extracting DNA from a biological sample, such as blood, hair, or saliva, and analyzing specific regions of the DNA that vary greatly among individuals. These regions, known as short tandem repeats (STRs), are highly variable and provide a distinct genetic profile for each person.

DNA profiling is widely used in forensic science for identifying suspects and victims in criminal investigations, as well as in paternity testing and genetic research. Its accuracy and reliability make it a powerful tool for solving crimes and resolving identity disputes.

- DNA extraction: A biological sample (e.g., blood, saliva) is collected and DNA is extracted.

- Amplification: Targeted regions of DNA, such as short tandem repeats (STRs), are amplified using PCR.

- Gel electrophoresis: Amplified DNA fragments are separated based on size using gel electrophoresis or capillary electrophoresis.

- Band pattern analysis: The separated DNA fragments create a distinct band pattern that serves as a genetic fingerprint.

- DNA profile generation: The pattern of bands is analyzed to create a unique DNA profile for the individual.

- Comparison: The DNA profile can be compared to profiles from other samples for identification or forensic analysis.

DNA/RNA/ Protein Synthesis

A neuron is a special cell that sends information to the body. It has three main parts: the cell body, dendrites, and axon. Dendrites receive signals from other cells, and the axon sends signals to other neurons or muscles. Neurons communicate using electrical impulses and chemicals called neurotransmitters. This network of neurons is crucial for activities like thinking, feeling, and moving.

Genetics Definition

DNA, RNA, and protein synthesis are processes that cells use to create proteins, which are essential for many functions in the body. Here's a simple explanation:

1. DNA (Deoxyribonucleic Acid)

   - DNA is the molecule that holds the genetic instructions for life.

   - It is like a blueprint that tells the cell how to make proteins.

2. Transcription (DNA to RNA)

   - The cell makes a copy of a gene (a small part of DNA) as RNA (Ribonucleic Acid).

   - This RNA copy is called messenger RNA (mRNA).

   - Think of mRNA as a message that carries instructions from the DNA in the nucleus to the rest of the cell.

3. Translation (RNA to Protein)

   - The mRNA travels to the ribosome, a part of the cell that makes proteins.

   - The ribosome reads the mRNA and translates the instructions to build a protein.

   - Proteins are made up of small building blocks called amino acids, which are put together in a specific order.

Applications of genes include:

1. Medical Treatments

   - Gene therapy can treat or prevent diseases by correcting defective genes or introducing new genes into a patient’s cells.

   - Personalized medicine uses genetic information to tailor treatments to individual patients, improving effectiveness and reducing side effects.

2. Agriculture

   - Genetic engineering creates crops with desirable traits such as resistance to pests, diseases, and environmental conditions, or improved nutritional content.

   - Genetically modified organisms (GMOs) help increase food production and security.

3. Forensic Science

   - DNA profiling identifies individuals based on their unique genetic makeup, which is crucial in criminal investigations and legal cases.

   - Paternity tests and identifying remains in disaster situations also rely on genetic analysis.

4. Biotechnology

Genes are used in the production of pharmaceuticals, such as insulin and other vital medications.

Genetic research contributes to developing new biotechnological tools and innovations, enhancing various industrial processes.

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