When referring to how organisms differ within a species, we use the term 'variation'. For example, a tabby cat and a ginger cat are both a type of domestic cat, but look different. Variation can be because of the following:
- The genes that have been passed down to them by their parents. So genetic causes (e.g. tongue rolling).
- The environmental conditions in which they have developed and evolved. So environmental causes (e.g. dyed hair in the case of humans).
- Or even a mix of both (e.g. height).
Plants and animals reproduce in different ways, the two being sexual and asexual reproduction.
- Sexual reproduction involves two haploid (containing 23 chromosomes as opposed to diploid which contains 46) sex cells (called gametes) coming into contact to form a zygote. This zygote won't be completely identical to either of the parents, but will have some of their genes carried over. Animals and most plants use this method.
- Asexual reproduction, on the other hand, can be done in various ways that don't involve two organisms coming into contact. A seed being released from a plant and being taken away by the wind to be planted in the ground is an example. This causes genetically identical offspring as a result. Some plants use this method such as spider plants (or Chlorophytum Comosum)
An allele is an alternate form of a gene, meaning it can have different outcomes. A genotype is a combination of these alleles, usually expressed in letters. The phenotype is the physical appearance of a genotype. For example:
Above is an example of a genotype containing two alleles: a dominant allele represented with a capital T and a recessive allele represented with a lower-case t. Because the two alleles are different, this genotype is heterozygous. If the alleles were the same i.e TT or tt, then it would be homozygous. In a heterozygous genotype, the dominant allele will always take effect, so in this example because it has a dominant allele which translates to being able to roll their tongue, this person will be able to roll their tongue. This is the phenotype because it is the characteristic that they get from this gene. It can only be if the genotype is homozygous recessive, meaning that it has two recessive alleles, that they will take effect, because there is no dominant allele to say otherwise. So, in this example:
- Tt will result in a tongue roller because there is a dominant allele for a tongue roller.
- TT will also result in this because there are two dominant alleles.
- tt will result in a non-tongue roller because there are two recessive alleles, both of which are for a non tongue roller.
DNA (Deoxyribonucleic Acid) - The arrangement of molecules and atoms that are the building blocks of a person and found in cell nuclei. This uses different proteins to RNA.
RNA (Ribonucleic Acid) - The arrangement of molecules and atoms that can be found in bacteria, virus' and protozoa. It uses different proteins to DNA
Double Helix - A molecule of DNA shaped like a twisted ladder. There are chemical cross-links between 2 strands formed by pairs of different bases.
Base - A section of a DNA molecule (guanine pairs with adenine, thymine pairs with cytosine).
Complementary - The description for a half of one pair of bases in relation to the other. (Pairs of bases which will fit together)
Gene - A short section of DNA, each gene "codes" for a specific protein by specifying the order in which amino acids must be join together. (forming genotypes and phenotypes)
Chromosome - One of the 46 (in Humans which gain 23 from each parent) separate molecules of DNA
Asexual reproduction - A form of reproduction where offspring are produced from a single organism, meaning the offspring's genes are inherited from that parent alone. (Cloning)
Sexual Reproduction - Reproduction where organisms are produced combining genetic information from two individuals (one male, one female). This means that the offspring inherits half of their genes from each parent.
Variation - any difference between cells individual organisms or groups of organisms of any species caused by either genetic differences or environmental factors.
Allele - A specific gene (an allele is not the name of a gene)
Dominant Allele - a gene whose effects will definitely be shown in the organism (two dominant alleles are co-dominant)
Recessive Allele - a gene whose effects will only be shown in the organism if both chromosomes have the gene. If there is a dominant, the recessive doesn't show.
Genotype - The combination of alleles an organism has (which codes for amino acids)
Phenotype - What an organism physically 'looks like' (the physical characteristics it has)
Carrier - An organism that has inherited a recessive gene and therefore a genetic trait or mutation but the trait is not displayed, nor the symptoms of the disease
Inherited Disease (A genetic disease) - a disease caused by an abnormality in an individual's genome. A genetic disease can be inherited from parents or by mutations in an pre-existing gene/group of genes
Homozygous - Having 2 identical forms of a gene
Heterozygous - Having 2 different forms of a gene
Mitosis - cell division process which causes the forming of identical cells to the parent
Meiosis - cell division process which causes the forming of different cells to the parent (and each other)
RNA (Ribonucleic Acid) - The arrangement of molecules and atoms that can be found in bacteria, virus' and protozoa. It uses different proteins to DNA
Double Helix - A molecule of DNA shaped like a twisted ladder. There are chemical cross-links between 2 strands formed by pairs of different bases.
Base - A section of a DNA molecule (guanine pairs with adenine, thymine pairs with cytosine).
Complementary - The description for a half of one pair of bases in relation to the other. (Pairs of bases which will fit together)
Gene - A short section of DNA, each gene "codes" for a specific protein by specifying the order in which amino acids must be join together. (forming genotypes and phenotypes)
Chromosome - One of the 46 (in Humans which gain 23 from each parent) separate molecules of DNA
Asexual reproduction - A form of reproduction where offspring are produced from a single organism, meaning the offspring's genes are inherited from that parent alone. (Cloning)
Sexual Reproduction - Reproduction where organisms are produced combining genetic information from two individuals (one male, one female). This means that the offspring inherits half of their genes from each parent.
Variation - any difference between cells individual organisms or groups of organisms of any species caused by either genetic differences or environmental factors.
Allele - A specific gene (an allele is not the name of a gene)
Dominant Allele - a gene whose effects will definitely be shown in the organism (two dominant alleles are co-dominant)
Recessive Allele - a gene whose effects will only be shown in the organism if both chromosomes have the gene. If there is a dominant, the recessive doesn't show.
Genotype - The combination of alleles an organism has (which codes for amino acids)
Phenotype - What an organism physically 'looks like' (the physical characteristics it has)
Carrier - An organism that has inherited a recessive gene and therefore a genetic trait or mutation but the trait is not displayed, nor the symptoms of the disease
Inherited Disease (A genetic disease) - a disease caused by an abnormality in an individual's genome. A genetic disease can be inherited from parents or by mutations in an pre-existing gene/group of genes
Homozygous - Having 2 identical forms of a gene
Heterozygous - Having 2 different forms of a gene
Mitosis - cell division process which causes the forming of identical cells to the parent
Meiosis - cell division process which causes the forming of different cells to the parent (and each other)
This song is about genetics and it was written by tfashady10/Mr. Lee. His YouTube channel link is here- https://www.youtube.com/user/tfashady410