How Traits Change - Part 1

How Traits Change - Part 1

• This unit module explores how natural selection and adaptations affect traits.
• The content covers the fundamental processes of DNA, replication, transcription, and translation, which determine traits.

Table of Contents

• Introduction to DNA
• DNA Replication
• DNA Transcription
• DNA Translation

How Does DNA Affect Traits?

• An organism's body cells utilize DNA codes to determine the genetic traits.
• Cells assemble molecules, following specific instructions.
• Genes provide the necessary instructions to organize molecules and express traits, such as eye color and seed shape.

Introduction

• An organism's body cells utilize genetic codes to define traits.
• Cells assemble molecules using instructions.
• Genes provide instructions.
• Traits like eye color and seed shape are expressed by molecules assembled as per these instructions.

The Structure of DNA

• Chromosome: Composed of proteins and deoxyribonucleic acid (DNA).
• Gene: A segment of DNA on a chromosome.
• DNA: An organism's genetic material.

DNA in a Human Cell

• Scientists estimate over 1 meter of DNA within a human cell.
• DNA coils tightly into chromosomes to fit within the cell.

The Structure of DNA (Continued)

• DNA strands in chromosomes coil tightly, creating space for more genes.
• The coiling process is similar to a spring.

A Complex Molecule

• DNA's shape resembles a twisted ladder and is called a double helix.

Discovery of DNA

• Rosalind Franklin and Maurice Wilkins conducted X-ray studies on DNA.
• Their X-ray analysis revealed DNA's helical structure.
• James Watson and Francis Crick developed a DNA model, building upon Franklin and Wilkins' findings.
• This model showed how DNA molecules bond to form a double helix.

Four Nucleotides Shape DNA

• A nucleotide consists of a nitrogen base, a sugar, and a phosphate group.
• Four types of nitrogen bases are present in DNA: Adenine, Cytosine, Thymine, and Guanine (A, C, T, G).

The Nitrogen Bases

• Nitrogen bases form the rungs of the DNA ladder.
• Adenine (A) bonds with Thymine (T).
• Cytosine (C) bonds with Guanine (G).
• Sugar-phosphate groups form the DNA ladder's sides.

Label Parts of a Nucleotide

• Nucleotides are composed of a nitrogenous base, a sugar, and a phosphate group.
• Visual representations depict these components.

A Closer Look

• Detailed diagrams showcase the chemical structures of nitrogen bases (A, T, C, and G).
• The pairings of A with T and C with G are highlighted.

Each Nucleotide

• Each nucleotide includes a nitrogen base, a sugar, and a phosphate group.
• Nitrogen bases create steps on the DNA ladder.
• Sugar-phosphate groups form the DNA's side rails.

What is Stored in DNA?

• DNA carries information or instructions for all biological processes.
• The instructions facilitate organism growth, maintenance, and reproduction.

Replication

• The process of copying DNA to produce identical copies.
• Cells contain DNA within chromosomes.
• When a cell divides, each new cell requires a copy of the chromosomes' DNA.
• Replication ensures identical DNA copies for the new cell.

DNA Replication Process

• Cells contain DNA in chromosomes.
• Each time a cell divides, all chromosomes must be copied.
• The copied DNA is identical to the original.
• Replication is the process of creating a new DNA molecule.

Making Proteins

• Proteins perform crucial functions in organisms, including digestive enzymes, support for muscle contraction and movement, providing support for the body, immune system support, and transporting molecules throughout cells.

Making Proteins (Continued)

• Every cell contains DNA, which carries the blueprint for proteins.
• Genes provide instructions for protein assembly.

The Importance of RNA

• Proteins are created using ribonucleic acid (RNA).

DNA vs. RNA

• DNA and RNA are both involved in protein synthesis.
• Differences: DNA is double-stranded, while RNA is usually single-stranded.
• RNA uses uracil (U) instead of thymine (T).
• RNA uses ribose sugar instead of deoxyribose.

Types of RNA

• Three main types of RNA exist: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA).
• These RNA types collaborate in protein production.

Messenger RNA (mRNA)

• Carries genetic code from DNA to the cytoplasm.
• Facilitates protein synthesis.

Transfer RNA (tRNA)

• Transports amino acids to the ribosome.
• Essential in protein formation.

Ribosomal RNA (rRNA)

• Forms part of ribosomes, crucial protein manufacturing organelles.

Transcription

• The process of copying a gene's DNA sequence into mRNA.
• The blueprint for protein synthesis.
• The initial step in creating proteins from DNA.

Transcription (Continued)

• mRNA nucleotides pair with corresponding DNA nucleotides during transcription.
• The completed mRNA molecule then exits the nucleus.

Translation

• The process of reading the mRNA code to assemble amino acids into proteins.
• This process involves mRNA, tRNA, and rRNA.

Translation (Continued)

• tRNA delivers amino acids to the ribosome.
• rRNA facilitates the chemical bonding of amino acids.
• mRNA is read, amino acids are linked, and a protein is formed.
• mRNA releases its animo acids.

Translating the RNA Code

• Protein synthesis utilizes a secret code.
• Protein makeup consists of amino acids.
• mRNA's nitrogenous base sequence determines the protein's amino acid sequence.
• Three nitrogen bases (codons) on mRNA specify a particular amino acid.