B6 that's inheritance variation and evolution in order to reproduce sexually gametes sex cells must be made this happens by myosis for example in the testes to make sperm the chromosomes in a diploid cell that is 23 pairs for us are copied similar chromosomes then pair up and the genes are swapped between them the cell then divides to make two diploid cells which then divide again along with the chromosomes themselves to make four haid cells ready to fuse with another gamt which in this case would be an egg this is one way that variation occurs in Offspring the resulting diploid cell then starts to divide via mitosis which is covered in paper one plants do this with pollen and egg cells but they can also reproduce asexually but as it doesn't evolve gametes the daughter cells will be genetically identical so a clone of the parent is made by mitosis an advantage of sexual reproduction is that variation occurs which can result in organisms becoming better suited to their environment more than this in a bit so more likely to survive an advantage for asex is that only one parent is needed so for example a plant on its Lonesome can still reproduce in order for the species to survive another thing that can do both is the parasite that causes malaria as can some fungi genome is the term given to all the genetic material in an organism this code is stored in DNA of course which is a two stranded polymer in a double helix shape a gene is a section of DNA that codes for a specific protein the Human Genome Project completed its initial goal in 2003 when scientists mapped out what every Gene is responsible for coding this is powerful because it can help us identify what genes cause diseases or inherited disorders genotype is the term given to what code is stored in your DNA specifically while phenotype is how that code is expressed in your characteristics what proteins are made it affects your physiology for triple you need to know that the monomers between the two strands are called nucleotides and they're made from a sugar and phosphate group of which there are four types A T C and G you don't need to know what the names are but a and t always match to each other in the sequence as do C and G every three of these bases we can call them are a code for an amino acid the sequence is copied by mRNA this copy is then taken out of the nucleus to a ribosome in the cell where amino acids are connected in the order needed which makes a protein the shape of which affects His function they need to be folded as well first har mutations can change a gene so much that it results in a protein being synthesized that doesn't do the job it's supposed to we now know that some DNA however doesn't directly code for proteins but it influences how other genes are expressed this is the realm of epigenetics and it's changing the way that we view DNA quite drastically back to double some characteristics are controlled by just one gene like color blindness these different types of the same gene are called alals usually characteristics are dependent on two or more genes though and them interacting dominant alals are those that result in a characteristic being expressed even if there is another alil present a recessive alil for example if you have the Al's Big B little B for eye color Big B be brown little B be blue you will have brown eyes it's only when there's no dominant alil in this case that the recessive alil is expressed so me having blue eyes I must have the gene little B little B Big B Big B or little B little B are called homozy as they only have one type of alil whereas Big B little B is what we call heterozygous we can use a punet square to predict the probability of a certain phenotype my parents have brown eyes but they both have heterozygous alals for eye color there are three different outcomes of these combining with a 25% chance of making me that's little be little be so I'm not so much one in a million more one in four my sister has brown eyes but her son has blue eyes so she must be Big B little B eye color is by the by but some alals can result in disorders being inherited for example polya extra fingers or toes which is caused by a dominant Al or cystic vibrosis which is caused by a recessive alil even if two parents don't have cystic fibrosis they could still be carrying the recessive alil so their child could have the disorder human DNA is contain in 23 pairs of chromosomes but only one pair determines sex if you have XX chromosomes you are female XY you're male the expression of these genes affects every cell in your body every aspect of your physiology we can also make a punet square for these as you can see there's a 50/50 chance of a child being male or female variation is a result of the genes inherited from an organism's parents and also environmental factors Charles Darwin's theory of evolution states that random variation in Offspring will result in some being better suited to their environment than others and so are more likely to survive and reproduce but like we've seen we know that our DNA is able to respond to the environment in order to turn genes on and off depending on whether they're needed or not for example there were some blind translucent skin mackerel that were found in a dark cave when they were bred with normal mackerel in sunlight they regained fully working eyes and opaque skin within a few Generations John Baptist Lark's Theory asserted that adaptation of variation is Guided by DNA in response to a changing environment this was scoffed at but we now know that there is some truth to this thanks to the discoveries made in epigenetics bacterial resistance is largely considered to be evidence of Darwin and Evolution bacteria divides mutations occur and inevitably a bacterium with an increased resistance to antibiotics will be produced that's why we only want to use them when absolutely necessary it also means you have to complete the whole course of antibiotics if you don't weaker bacteria will have been killed off but more resistant ones will still be there and then they'll reproduce and make you even more ill if organisms are able to produce fertile offspring we say they're of the same species tigers and lions have been known to make lier Offspring but as they're infertile we don't consider tigers and lions to be the same species we can selectively breed living things with desired characteristics to enhance these for example breeding dogs to produce breeds like labrador's colleagues and if you're into undesirable characteristics pugs too advancements in biology over the last few decades mean that we can also genetically modify organisms if we don't want to wait for selective breeding to do the job or when it can't actually achieve what we want it to for good or ill for example scientists have genetically modified bacteria to produce insulin which can be harvested and used to treat people with diabetes genetically modifying crops is one way of boosting their yields or nutritional value for example gold and rice has a gene inserted into it that produces vitamin A it was developed to combat diets in certain areas that were lacking in this other GM crops have been modified to be more resistant to diseases for example the process of genetic engineering goes as follows a gene is chemically cut from the organ organism that has the desired characteristic this is done using enzymes for example the gene from a jellyfish that causes it to glow in the dark this is then inserted into a vector like a bacteria plasmid or virus that in turn inserts the gene into another organism say a bunny rabbit but it must be done in the early stage of its development say just after the Yoke has been fertilized as this is the only way you can be sure that the gene will be present in every cell of the bunny as it grows by the way I didn't make up this example this has actually been done fossils are the remains of organisms that died a very long time ago the classic fossils we think about are the bones that we dig up but they're not strictly speaking bones anymore in fact minerals have replaced the organic material to effectively leave Rock in exactly the same shape as the bone sometimes there can still be organic tissue Left Behind if the conditions for Decay are not present Footprints left in mud that have hardened over time for example are also considered fossils as well as as any other trace of an organism it doesn't have to be the organism itself cloning is triple only making exact copies of plants is easy just take cuttings off a plant put them in the ground and that does the job you can also go the slightly harder route by cloning from a tissue culture that is cloning from a small group of cells this can be helpful for preserving some species from going extinct cloning animals is more difficult you can split embryo cells up just after fertilization then put them into surrogate mothers essentially you're forcing identical twins but you won't know exactly what you're getting until they've developed so if you have a fully grown animal that you want to clone you take the nucleus from one of its cell say in his skin then insert that into another's egg cell it's essentially now a fertilized egg shocking the egg jump starts the development process and it starts to divide it's then inserted into another female womb where it continues to develop classification car lus classified organisms into Kingdom film class order family genus and species a good pneumonic for this is King Philip came over for good soup the binomial a Latin name for an organism is just the genus and species combined as time went on it turned out that another level above kingdom was needed domain the three domains are ARA that's primitive bacteria normal or true bacteria and ukara that's everything else of course with DNA and nucleus of the cells you should know about eukariotic cells from paper one ARA by the way are often found in extreme environments on the earth they can therefore be called extremophiles so I hope you found that helpful leave a like if you did and pop any questions or comments below and I'll see you in the next video