6.1.6
Genetic Inheritance
Mutations
Mutations
A mutation is a permanent change in the nucleotide sequence of DNA. Mutations happen continuously and normally only slightly affect proteins or don't affect them at all. Occasionally, a mutation may change the structure or shape of a protein. All genetic variants arise from mutations.
Undesirable change
Undesirable change
- The outcome of a mutation is almost always detrimental to protein function.
- For example, in enzymes, the substrate may no longer be able to bind to the active site. In structural proteins, their strength may be reduced.
- Some regions of DNA do not encode protein sequences.
- The term given to these sections is non-coding DNA.
Survival advantage
Survival advantage
- More rarely, a mutation may give a survival advantage, such as resistance to an antibiotic in bacteria.
- These mutations can be beneficial and represent the foundation of evolution by natural selection.
Alleles
Alleles
Alleles are different forms of the same gene. Humans have pairs of every gene and in one gene, each half of the pair may have different alleles. People's characteristics are determined by the alleles that they have. Alleles can either be dominant or recessive:
Dominant Alleles
Dominant Alleles
- A dominant allele is always expressed, regardless of the identity of the other allele.
- It only needs one copy present to be expressed (BB or Bb).
- It is represented by a capital letter, e.g. B.
- If B is the allele for brown eyes:
- When a person has a copy of the B allele, they will have brown eyes, no matter what other allele is present.
Recessive Alleles
Recessive Alleles
- A recessive allele is only expressed if the other allele is also recessive.
- It is represented by a lowercase letter e.g. b. It needs two copies to be present to be expressed (bb).
- If b is the allele for blue eyes:
- A person can only have blue eyes if both of their alleles are b.
Genotype vs Phenotype
Genotype vs Phenotype
When talking about the inheritance of characteristics, we use the words genotype and phenotype:
Genotype
Genotype
- Genotype refers to the combination of alleles an organism has.
- If the two alleles are different, we say that the person is heterozygous (Bb).
- If the two alleles are the same, we say that the person is homozygous (BB or bb).
Phenotype
Phenotype
- A phenotype is an observed characteristic of an individual.
- The phenotype is determined by the interaction between the genotype and environment.
- Earlobes being attached or free is an example of a phenotype, where the alleles present will determine a characteristic, unless the environment interferes.
1Cell Biology
1.1What's in Cells?
1.1.1Types of Cells
1.1.2Properties of Prokaryotes
1.1.3Standard Form
1.1.4Standard Form - Calculations
1.1.5Addition in Standard Form - Calculations
1.1.6Subtraction in Standard Form - Calculations
1.1.7Multiplication in Standard Form - Calculations
1.1.8Division in Standard Form - Calculations
1.1.9Animal Cells
1.1.10Plant Cells
1.1.11Differences Between Animal & Plant Cells
1.1.12Bacterial Cells
1.1.13Types of Cells HyperLearning
1.1.14Cell Specialisation in Animals
1.1.15Sperm Cells
1.1.16Nerve Cells
1.1.17Muscle Cells
1.1.18Cell Specialisation in Plants
1.1.19Microscopy
1.1.20Developments in Microscopy
1.1.21Microscope Practical
1.1.22Microscopy - Calculations
1.1.23Culturing Microorganisms
1.1.24Contamination
1.1.25Avoiding Contamination
1.1.26Calculating Bacteria
1.1.27Calculating Bacteria - Calculations
1.1.28End of Topic Test - What's in Cells?
1.1.29Exam-Style Questions - Cell Structure & Microscopy
1.2Cell Division
1.3Transport in Cells
1.3.1Diffusion
1.3.2Factors Affecting Diffusion
1.3.3Surface Area : Volume
1.3.4Surface Area : Volume - Calculations
1.3.5Exchange Surfaces
1.3.6Examples of Exchange Surfaces
1.3.7Osmosis
1.3.8Osmosis Practical
1.3.9Active Transport
1.3.10Transport in Cells
1.3.11End of Topic Test - Cell Division & Transport
1.3.12Grade 9 - Cell Transport
2Organisation
2.1Principles of Organisation
2.2Enzymes
2.2.1Enzymes
2.2.2Enzymes HyperFlashcards
2.2.3Rate of Reaction
2.2.4Calculating Rate of Reaction
2.2.5Rate of Reaction - Calculations
2.2.6Digestion
2.2.7Bile
2.2.8Examples of Digestive Enzymes - Amylase
2.2.9Examples of Digestive Enzymes - Protease
2.2.10Examples of Digestive Enzymes - Lipase
2.2.11Testing for Biological Molecules
2.2.12End of Topic Test - Organisation & Enzymes
2.2.13Grade 9 - Enzymes
2.2.14Exam-Style Questions - Enzymes
2.3Circulatory System
2.3.1Types of Blood Vessel
2.3.2Blood Vessels - Arteries
2.3.3Blood Vessels - Capillaries
2.3.4Blood Vessels - Veins
2.3.5The Heart - Structure
2.3.6The Heart - Function
2.3.7Important Blood Vessels
2.3.8Double Circulatory System
2.3.9Gas Exchange
2.3.10Gas exchange - Calculations
2.3.11Alveoli
2.3.12Blood Components
2.3.13Platelets
2.3.14Red Blood Cells
2.3.15White Blood Cells
2.3.16End of Topic Test - Circulatory System
2.4Non-Communicable Diseases
2.4.1Health Issues
2.4.2Disease Interactions
2.4.3Sampling
2.4.4Sampling - Calculations
2.4.5Risk Factors
2.4.6Examples of Risk Factors
2.4.7Risk Factor Graphs
2.4.8Coronary Heart Disease
2.4.9Heart Valve Disease
2.4.10Heart Failure
2.4.11Treating Heart Disease
2.4.12Cancer
2.4.13Cancer Risk Factors
2.4.14End of Topic Test - Non-Communicable Diseases
2.4.15Exam-Style Questions - Coronary Heart Disease
2.5Plant Tissues, Organs & Systems
3Infection & Response
3.1Communicable Disease
3.1.1Spreading Disease
3.1.2Viruses
3.1.3Other Pathogens
3.1.4Human Defence Systems
3.1.5Human Defence Systems 2
3.1.6Grade 9 - Immune System
3.1.7Antibiotics
3.1.8Drug Development
3.1.9Drug Testing
3.1.10Drug Testing / Efficacy - Calculations
3.1.11End of Topic Test - Communicable Diseases
3.1.12Exam-Style Questions - Microorganisms & Disease
3.2Monoclonal Antibodies
4Bioenergetics
4.1Photosynthesis
5Homeostasis & Response
5.1Homeostasis
5.2The Human Nervous System
5.2.1The Nervous System
5.2.2The Nervous System HyperFlashcards
5.2.3Synapses
5.2.4Reflexes
5.2.5Exam-Style Questions - Nervous System
5.2.6The Brain
5.2.7Eye Anatomy
5.2.8Eye Function
5.2.9Control of Body Temperature
5.2.10Warming Up & Cooling Down
5.2.11Body Temperature HyperLearning
5.2.12End of Topic Test - Human Nervous System
5.3Hormonal Coordination in Humans
5.3.1Endocrine System
5.3.2Thyroxine & Adrenaline
5.3.3Blood Glucose
5.3.4Diabetes
5.3.5Control of Water Balance
5.3.6Urine
5.3.7Dialysis
5.3.8Transplants
5.3.9Puberty
5.3.10Menstruation
5.3.11Contraception
5.3.12Contraception 2
5.3.13Hormones for Infertility
5.3.14End of Topic Test - Homeostasis & Hormones
5.3.15Grade 9 - Hormonal Coordination
5.3.16Exam-Style Questions - Hormones & Contraception
6Inheritance, Variation & Evolution
6.1Reproduction
6.1.1Reproduction
6.1.2Reproduction 2
6.1.3Genome
6.1.4DNA
6.1.5Protein Synthesis
6.1.6Genetic Inheritance
6.1.7Genetic Crosses
6.1.8Inherited Disorders
6.1.9Inherited Disorders 2
6.1.10Genetic Crosses - Calculations
6.1.11Genome Screening & Sex Determination
6.1.12End of Topic Test - Reproduction
6.1.13Exam-Style Questions - DNA & Genetics
6.2Variation & Evolution
6.3Genetics & Evolution
7Ecology
7.1Adaptations & Interdependence
7.2Organisation of Ecosystems
7.3Biodiversity
7.4Trophic Levels
Jump to other topics
1Cell Biology
1.1What's in Cells?
1.1.1Types of Cells
1.1.2Properties of Prokaryotes
1.1.3Standard Form
1.1.4Standard Form - Calculations
1.1.5Addition in Standard Form - Calculations
1.1.6Subtraction in Standard Form - Calculations
1.1.7Multiplication in Standard Form - Calculations
1.1.8Division in Standard Form - Calculations
1.1.9Animal Cells
1.1.10Plant Cells
1.1.11Differences Between Animal & Plant Cells
1.1.12Bacterial Cells
1.1.13Types of Cells HyperLearning
1.1.14Cell Specialisation in Animals
1.1.15Sperm Cells
1.1.16Nerve Cells
1.1.17Muscle Cells
1.1.18Cell Specialisation in Plants
1.1.19Microscopy
1.1.20Developments in Microscopy
1.1.21Microscope Practical
1.1.22Microscopy - Calculations
1.1.23Culturing Microorganisms
1.1.24Contamination
1.1.25Avoiding Contamination
1.1.26Calculating Bacteria
1.1.27Calculating Bacteria - Calculations
1.1.28End of Topic Test - What's in Cells?
1.1.29Exam-Style Questions - Cell Structure & Microscopy
1.2Cell Division
1.3Transport in Cells
1.3.1Diffusion
1.3.2Factors Affecting Diffusion
1.3.3Surface Area : Volume
1.3.4Surface Area : Volume - Calculations
1.3.5Exchange Surfaces
1.3.6Examples of Exchange Surfaces
1.3.7Osmosis
1.3.8Osmosis Practical
1.3.9Active Transport
1.3.10Transport in Cells
1.3.11End of Topic Test - Cell Division & Transport
1.3.12Grade 9 - Cell Transport
2Organisation
2.1Principles of Organisation
2.2Enzymes
2.2.1Enzymes
2.2.2Enzymes HyperFlashcards
2.2.3Rate of Reaction
2.2.4Calculating Rate of Reaction
2.2.5Rate of Reaction - Calculations
2.2.6Digestion
2.2.7Bile
2.2.8Examples of Digestive Enzymes - Amylase
2.2.9Examples of Digestive Enzymes - Protease
2.2.10Examples of Digestive Enzymes - Lipase
2.2.11Testing for Biological Molecules
2.2.12End of Topic Test - Organisation & Enzymes
2.2.13Grade 9 - Enzymes
2.2.14Exam-Style Questions - Enzymes
2.3Circulatory System
2.3.1Types of Blood Vessel
2.3.2Blood Vessels - Arteries
2.3.3Blood Vessels - Capillaries
2.3.4Blood Vessels - Veins
2.3.5The Heart - Structure
2.3.6The Heart - Function
2.3.7Important Blood Vessels
2.3.8Double Circulatory System
2.3.9Gas Exchange
2.3.10Gas exchange - Calculations
2.3.11Alveoli
2.3.12Blood Components
2.3.13Platelets
2.3.14Red Blood Cells
2.3.15White Blood Cells
2.3.16End of Topic Test - Circulatory System
2.4Non-Communicable Diseases
2.4.1Health Issues
2.4.2Disease Interactions
2.4.3Sampling
2.4.4Sampling - Calculations
2.4.5Risk Factors
2.4.6Examples of Risk Factors
2.4.7Risk Factor Graphs
2.4.8Coronary Heart Disease
2.4.9Heart Valve Disease
2.4.10Heart Failure
2.4.11Treating Heart Disease
2.4.12Cancer
2.4.13Cancer Risk Factors
2.4.14End of Topic Test - Non-Communicable Diseases
2.4.15Exam-Style Questions - Coronary Heart Disease
2.5Plant Tissues, Organs & Systems
3Infection & Response
3.1Communicable Disease
3.1.1Spreading Disease
3.1.2Viruses
3.1.3Other Pathogens
3.1.4Human Defence Systems
3.1.5Human Defence Systems 2
3.1.6Grade 9 - Immune System
3.1.7Antibiotics
3.1.8Drug Development
3.1.9Drug Testing
3.1.10Drug Testing / Efficacy - Calculations
3.1.11End of Topic Test - Communicable Diseases
3.1.12Exam-Style Questions - Microorganisms & Disease
3.2Monoclonal Antibodies
4Bioenergetics
4.1Photosynthesis
5Homeostasis & Response
5.1Homeostasis
5.2The Human Nervous System
5.2.1The Nervous System
5.2.2The Nervous System HyperFlashcards
5.2.3Synapses
5.2.4Reflexes
5.2.5Exam-Style Questions - Nervous System
5.2.6The Brain
5.2.7Eye Anatomy
5.2.8Eye Function
5.2.9Control of Body Temperature
5.2.10Warming Up & Cooling Down
5.2.11Body Temperature HyperLearning
5.2.12End of Topic Test - Human Nervous System
5.3Hormonal Coordination in Humans
5.3.1Endocrine System
5.3.2Thyroxine & Adrenaline
5.3.3Blood Glucose
5.3.4Diabetes
5.3.5Control of Water Balance
5.3.6Urine
5.3.7Dialysis
5.3.8Transplants
5.3.9Puberty
5.3.10Menstruation
5.3.11Contraception
5.3.12Contraception 2
5.3.13Hormones for Infertility
5.3.14End of Topic Test - Homeostasis & Hormones
5.3.15Grade 9 - Hormonal Coordination
5.3.16Exam-Style Questions - Hormones & Contraception
6Inheritance, Variation & Evolution
6.1Reproduction
6.1.1Reproduction
6.1.2Reproduction 2
6.1.3Genome
6.1.4DNA
6.1.5Protein Synthesis
6.1.6Genetic Inheritance
6.1.7Genetic Crosses
6.1.8Inherited Disorders
6.1.9Inherited Disorders 2
6.1.10Genetic Crosses - Calculations
6.1.11Genome Screening & Sex Determination
6.1.12End of Topic Test - Reproduction
6.1.13Exam-Style Questions - DNA & Genetics
6.2Variation & Evolution
6.3Genetics & Evolution
7Ecology
7.1Adaptations & Interdependence
7.2Organisation of Ecosystems
7.3Biodiversity
7.4Trophic Levels
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