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Biology

Inheritance, variation and evolution

Genetic inheritance

Carrying out a genetic cross

GCSE Biology: Inheritance, Variation and Evolution Notes PDF (Part 1)

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GCSE Biology: Inheritance, Variation and Evolution Notes PDF (Part 1)

Biology

Revision note

Inheritance, variation and evolution is a crucial topic in GCSE Biology. This comprehensive guide covers DNA structure, protein synthesis, mutations, and the Human Genome Project, providing essential knowledge for students preparing for exams.

• DNA (deoxyribonucleic acid) is the foundation of genetic information
• Genes code for specific proteins, determining cell types and inherited characteristics
• Understanding the human genome offers insights into diseases and human evolution
• Protein synthesis involves transcription and translation processes
• Mutations can alter DNA sequences, potentially affecting protein function

29/04/2023

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Protein Functions and DNA Replication

For AQA GCSE Biology Topic 6 questions, it's important to understand protein functions and DNA replication. Proteins have various roles in the body, determined by their unique shapes.

Examples of protein functions include:

Enzymes: Biological catalysts that speed up chemical reactions
Hormones: Used to carry messages around the body
Structural proteins: Provide physical strength
Antibodies: Part of the immune system
Carrier proteins: Transport substances in the body

DNA replication is a crucial process for cell division and inheritance:

The double helix unwinds and bases unzip
The two strands separate
New complementary bases pair up
Each DNA molecule winds up again, creating two identical helixes

Highlight: DNA replication ensures that each new cell receives an exact copy of the genetic information.

INHERITANCE
ONA:
+ VARIATION + EVOLUTION
1) DNA stands for deoxyribonucleic acid.
L> it is the chemical that all genetic information.
in a c

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DNA Structure and Protein Synthesis

In GCSE Biology inheritance exam questions, understanding DNA structure and protein synthesis is crucial. DNA strands are polymers made up of monomers called nucleotides.

Vocabulary: Nucleotides consist of one sugar molecule, one phosphate molecule, and one base.

There are four different bases in DNA: A, T, C, and G. These bases pair up in a specific way:

Definition: Complementary base pairing occurs between A and T, and C and G, joined by hydrogen bonds.

The order of bases in a gene determines the order of amino acids in a protein. Each amino acid is coded by a sequence of three bases in a gene.

Protein synthesis involves two main steps:

Transcription in the nucleus
Translation in the cytoplasm

Highlight: mRNA (messenger RNA) carries the genetic code from DNA in the nucleus to ribosomes in the cytoplasm, where proteins are made.

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DNA Structure and Function

Inheritance, variation and evolution GCSE Biology begins with understanding DNA structure. DNA, or deoxyribonucleic acid, is the chemical that contains all genetic information in a cell. It determines inherited characteristics and is found in the nucleus within chromosomes.

Definition: DNA (deoxyribonucleic acid) is the chemical that all genetic information in a cell is made up from.

DNA is composed of two polymer strands coiled together in a double helix shape. Chromosomes come in pairs, and genes are small sections of DNA found on chromosomes.

Highlight: Genes code for specific proteins by determining the sequence of amino acids.

The human genome, which is the entire set of genetic material in an organism, has significant implications for scientific research and medical advancements.

Example: Understanding the human genome allows scientists to identify genes linked to different types of diseases, potentially leading to better treatments.

Scientists can also use genomic information to study human evolution and migration patterns, tracing our ancestry back to a common African ancestor.

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Mutations and Their Effects

Genetic variation GCSE Biology topics often include mutations. A mutation is a random change in an organism's DNA, which can sometimes be inherited.

Definition: A mutation is a random change in an organism's DNA that can alter the sequence of bases in a gene, producing a genetic variant.

Mutations occur continuously and can be spontaneous or induced by exposure to certain substances or radiation. While most mutations have little or no effect on proteins, some can significantly impact protein function.

Example: If a mutation changes an enzyme's active site shape, it may not be able to bind to its substrate, affecting its function.

Types of mutations include:

Insertions: A new base is inserted into the DNA sequence
Deletions: A base is removed from the DNA sequence

Highlight: Mutations in non-coding DNA can alter how genes are expressed, potentially affecting an organism's characteristics.

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