Tackling and mastering inheritance, selection and variation

This video is just an overview of what to expect in this section :)

When you first learn about chromosomes, DNA, genes and alleles, it can all be quite confusing. I've gone through it slowly so that you can visualise what each term means. 

This is a video lecture, where you will be able to..

• Define inheritance
• State the meaning of chromosome, gene, DNA and allele
• Define a diploid and haploid nucleus
• State how many chromosomes there are in a human cell and human sex cell
• State how to determine the sex of a person by looking at the karyotype

This is a video lecture, where I take you through the steps from DNA to proteins. By the end of the lecture, you should be able to

• Explain how DNA controls cell function by controlling what proteins are made.
• State 3 important proteins in the body: enzymes, antibodies and receptors for neurotransmitters
• Explain what the genetic code is
• Explain how the sequence of bases in a gene code for the correct order of amino acids in a protein
• Explain briefly how a protein is made

Mitosis can be quite hard to get your head around. I've explained it briefly in this video, so that you can visualise the different steps and see why this nuclear division is important in life processes.

By the end of this video, you should be able to

• Define mitosis
• State the use of mitosis in growth, repair, replacement of cells and asexual reproduction
• Define meiosis and state its role in gamete function
• State that chromosomes are duplicated before mitosis
• Outline what happens to chromosomes during mitosis
• State the difference between embryonic stem cells and adult stem cells and describe the role of stem cells

Meiosis and Mitosis may appear to be very similar at first, but once you watch the different steps and see how they compare side by side, you will figure out why meiosis results in cells with half the number of chromosomes as the parent cell.

By the end of this lesson, you should be able to

• Define meiosis
• Explain how meiosis produces variation by forming new combinations of maternal and paternal chromosomes
• State the differences between mitosis and meiosis

Inheritance involves a lot of new terms: phenotypes, genotypes, recessive, dominant! In this lecture, I go through what each term means and how to use do a test cross and use a Punnett Square. By the end of this lecture, you should be able to

• Use pedigree diagrams to show how features are inherited
• Distinguish between genes and alleles
• Define phenotype, genotype, homozygous, heterozygous, dominant and recessive

Doing test crosses at first is quite tricky, but once you have gone through the steps that I show you in this video lecture, it will become a piece of cake! There are different phenotypic ratios that you need to learn too, so I will highlight these to you.

By the end of this lecture, you will be able to

• Define monohybrid inheritance
• Use genetic diagrams to predict the results of monohybrid crosses and calculate phenotypic ratios
• Use Punnett squares in crosses which result in more than one genotype to work out and show the possible different genotypes
• Explain how to use a test cross to identify an unknown genotype

You've just got your head about monohybrid inheritance! Now, you are going to learn about how certain alleles are co-dominant and result in different phenotypes to the parents. Don't worry, this video lecture goes through it so you will be a pro by the end :)

By the end of this lecture, you will be able to 

• Explain the term codominance
• Describe the inheritance of ABO blood groups
• State the possible allele combinations of people with blood groups A, B, AB and O.
• Use Punnett squares to determine the resulting blood groups of children from parents who have different blood groups.

Sex linkage...why is it if a man has a defective allele for a sex linked disease, he has the disease and yet his sister, who also has the defective allele, doesn't? You will soon find this out.

By the end of this video lecture, you will be able to

• Describe how sex is determined and inherited in humans
• Describe colour blindness as an example of sex linkage
• Define a sex linked characteristic
• Use genetic diagrams to predict the results of crosses involving sex linkage

In this video lecture, I go through examples with you of how to figure out the genotypes and phenotypes of individuals in pedigree diagrams.

Download the pdf of flash cards, cut them out and use them for revision.

Blank spaces have been left between the sections incase you want to create your own flash cards.

This video gives you an overview of what to expect in this section :)

By the end of this video lecture, you should be able to

• Define variation
• Identify and explain examples of variation
• Distinguish between genetic variation and phenotypic variation
• State the differences between continuous and discontinuous variation
• Draw the typical graphs of continuous and discontinuous variation
• State that phenotypic variation is caused by both genetic and environmental factors
• State that discontinuous variation is mostly caused by genes alone such as the different blood groups
• Give examples of genetic and environmental factors that cause phenotypic variation

Gene mutations are so interesting! In this video, I explain how mutations result in different alleles. There's a disease called sickle cell anaemia which is due to a mutation and results in your red blood cells having a different shape to normal red blood cells. I've gone beyond the syllabus and explained a bit about cancer because it links in nicely with mutations.

By the end of this lesson, you will be able to

• Define the term mutation
• State that mutation is the way in which new alleles are formed
• Describe the possible effects of radiation and certain chemicals on the rate of mutations
• Describe sickle cell anaemia as an example of a mutation
• Briefly describe how gene mutations can result in cancer

Sickle cell anaemia is such an interesting genetic disorder. In this lesson, you are going to learn about how having one allele for the abnormal haemoglobin will give you resistance to malaria.

By the end of this lesson, you will be able to

• Describe sickle cell anaemia as an example of a gene mutation
• Describe the symptoms of sickle cell anaemia
• Explain the distribution of sickle cell allele in human populations with reference to the distribution of malaria
• Use a punnett square to work out the genotype and phenotype of children from parents who have the sickle cell trait
• State that the heterozygous condition for sickle cell trait gives resistance to malaria

It's easy to pick up how an animal is adapted to it's environment, but what about plants? In this video, I'll explain to you how plants that live in water and plants that live in the desert are adapted to their environments.

By the end of this lesson, you should be able to

• Define adaptive feature
• Define fitness
• Interpret images or other information about a species to describe its adaptive features
• Explain the adaptive features of hydrophytes and xerophytes to their environments

Using examples that you can visualise makes natural selection much easier to understand. By the end of this video lecture, you should be able to

• Describe natural selection
• Describe evolution as the change in adaptive features of a population over time as a result of natural selection
• Define the process of adaptation

Antibiotic resistant bacteria is becoming a real problem these days. How do bacteria become antibiotic resistant? I this video lecture, I will explain how natural selection is linked to antibiotic resistant bacteria, as well as other examples like the peppered moth, sickle cell trait and Darwin's finches.

By the end of this video, you should be able to

• Describe the development of antibiotic resistant bacteria as an example of evolution by natural selection
• Give other examples of natural selection: Darwin's finches, peppered moth, sickle cell anaemia trait

Humans always want the best out of their crops and animals. A process called artificial selection or selective breeding results in these kind of animals or crops being produced.

By the end of this lecture, you should be able to

• Describe the role of selective breeding in producing varieties of animals and plants with increased economic importance
• Describe examples of artificial selection
• Outline how selective breeding is carried out
• State the differences between artificial and natural selection

These are flash cards on terminology or facts that you might find helpful with learning this section. Download the pdf of flash cards, cut them out and use them for revision.

Blank spaces have been left between the sections incase you want to create your own flash cards.