Sexual Reproduction & Inheritance

Now lets meet their children! Starter: Characteristics from sexual reproduction leading to variation Characteristics Meet our Mr Men And our Little Misses Now lets meet their children!

Starter: Characteristics from sexual reproduction leading to variation

Objective Success Criteria To investigate how sexual reproduction can lead to variation within a species. Success Criteria By the end of the lesson I: can identify the two types of reproduction as sexual and asexual reproduction. can explain the differences between sexual and asexual reproduction in that sexual reproduction leads to variation because the genes from two parents are mixed to create a new individual whereas in asexual reproduction there is only one parent and hence no mixing. can explain in detail how sexual reproduction leads to variation within a species using the correct scientific key words.

Where do chromosomes come from? STARTER In most cells chromosomes are matched in pairs based on their size and shape. Where do chromosomes come from? Each pair of chromosomes contains one chromosome that has been inherited from each parent. chromosome from male parent chromosome from female parent

What’s in your genes? Inside the NUCLEUS of every one of your cells there are CHROMOSOMES. CHROMOSOMES are coiled up DNA strands. On each CHROMOSOME there are several thousand GENES. GENES are shorter sections of DNA that code for particular CHARACTERISTICS GENES provide instructions to make PROTEINS that control the functions of the cell and therefore determining how the body functions (characteristics)

Asexual Reproduction Asexual reproduction only involves 1 parent and so gives rise to offspring known as CLONES. Why? Daffodils can reproduce both Asexually and Sexually! Why would this make these plants more successful? Explain the differences between the two types of offspring?

Sexual Reproduction All living things can reproduce. In most animals and plants this usually happens by sexual reproduction. This is when a male and a female mate, and produce offspring using sex cells. The young plants or animals will have similar characteristics to their parents but will not be identical to them.

Sexual reproduction involves special sex cells called gametes. Male animals produce gametes called sperm cells and female animals make gametes called egg cells. Who's related?

Draw and label sex organs in plants In plants, the female sex cells are also called egg cells; the male sex cells are found in pollen grains in the anthers.

What is the difference between Pollination and fertilisation Pollination is ……………….. Fertilisation is …………………..

Variation Why is variation important ??? Whole population will not be wiped out Increase genes in a population Allow survival of the fittest

Sexual reproduction is VERY risky as it relies on the joining of two sex cells. Even so, sexual reproduction is SO important for variation amongst species and hence survival that it can be seen in almost all types of plants and animals THINK If one parent has blue eyes and one parent has brown eyes what colour eyes will their children have? Can you prove this?

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Each pair of genes affects a different characteristic Each gene can have a different form. The versions of the same gene are called ALLELES Each parent will have two chromosomes that contain the gene for eye colour. Gene for eye colour How can we represent the different eye colours? Blue eyes Brown eyes

I can explain how sexual reproduction leads to variation Different versions of the same gene are known as ALLELES. For example, blue and brown are two alleles for eye colour. If we inherit one chromosome from each parent what ALLELES will the offspring have?

I can explain how sexual reproduction leads to variation The Brown allele is DOMINANT over the blue allele. What colour eyes will the offspring have? All the offspring will have Brown eyes Some alleles are DOMINANT over other forms of the gene. This means that the DOMINANT allele will always be expressed (shown) over the RECCESSIVE allele. What does this mean?

I can explain how sexual reproduction leads to variation Punnett Squares B B Alleles Brown = B Blue = b Genotype Homozygous Brown = BB Homozygous Blue= bb b b What does HOMOZYGOUS mean?

I can explain how sexual reproduction leads to variation Can two people with brown eyes have blue eyed children? Genotype Brown = Bb Homozygous or heterozygous?

I can explain how sexual reproduction leads to variation PHENOTYPE means the physical expression of the gene. i.e. what colour the eyes will be GENOTYPE is the pair of alleles for a characteristic i.e. BB or Bb or bb

I can explain how sexual reproduction leads to variation

There are genes that decide whether; INVESTIGATION There are genes that decide whether; your earlobes are attached close to the side of your head or hang freely your thumb is straight or curved you have dimples when you smile you have hair on the second segment of your ring finger You are going to complete an investigation on babies lobes! HANG FREELY STRAIGHT ATTACHED CURVED

PLENARY In most cells chromosomes are matched in pairs based on their size and shape. Recap How many chromosomes? How many pairs? Where are they found?

Objective Success Criteria To investigate how sexual reproduction can lead to variation within a species. Success Criteria By the end of the lesson I: can identify the two types of reproduction as sexual and asexual reproduction. can explain the differences between sexual and asexual reproduction in that sexual reproduction leads to variation because the genes from two parents are mixed to create a new individual whereas in asexual reproduction there is only one parent and hence no mixing. can explain in detail how sexual reproduction leads to variation within a species using the correct scientific key words.