Inheritance- Biology

• A mutation called an insertion is when a ew base is added which changes the way the protein or amino acid is read which affects the rest of the bases in the sequence
• A mutation called a deletion is when a base is deleted which changes the way its read
• A mutation called a substitution means that a random base is changed for something else
• Three functions of proteins include enzymes, hormones and structural proteins
• Structural proteins give strength and support to cells and tissues
• mRNA acts as a messenger where it copies the code from the DNA and carries it to the ribosome. The correct amino acids are brought to the ribosomes in the correct order by carrier molecules
• A gene is a section of DNA that codes for a specific protein.
• Triplets of bases codes for a singular amino acid
• Amino acids join together to form a protein. The proteins specific shape means that its ideal for its function
• Sexual reproduction involves the fusion of male and female gametes. Because there are two parents, the offspring contains a mixture of their parents genes
• in humans, each gametes contains 23 chromosomes- half the number in a normal cell. Instead of having two of each chromosome, it only has one
• During sexual reproduction, the sperm and the egg cell fuse together to form a cell with the full number of chromosomes- half from the mother, half from the father
• In asexual reproduction, only one parent is involved. There is no genetic variation between parent and offspring. They are genetically identical and are called clones
• When a cell divides to form gametes: copies of the genetic information are made. the cell divides twice to form four gametes, each with a single set of chromosomes. all gametes are genetically different from each other.
• Gametes join at fertilisation to restore the normal number of chromosomes. The new cell divides by mitosis. The number of cells increases. As the embryo develops cells differentiate.
• Advantages of sexual reproduction: produces variation in the offspring, if the environment changes variation gives a survival advantage by natural selection, offspring can inherit traits from both parents, natural selection can be speeded up by humans in selective breeding to increase food production.
• Advantages of asexual reproduction: only one parent is needed, more time and energy efficient, faster than sexual reproduction, many identical offspring are produced when the conditions are favourable
• Malarial parasites reproduce asexually in the human host, but sexually in the mosquito.
• Many fungi reproduce asexually by spores but also reproduce sexually to give variation.
• Many plants produce seeds sexually, but also reproduce asexually by runners such as strawberry plants, or bulb division such as daffodils.
• The genome of an organism is the entire genetic material of that organism. The whole human genome has now been studied and this will have great importance for medicine in the future.
• Studying the human genome is important in the search for genes linked to disease, understanding and treatment of inherited disorders, and is useful in tracing migration patterns from the past
• Proteins are synthesised on ribosomes, according to a template. Carrier molecules bring specific amino acids to add to the growing protein chain in the correct order.
• When the protein chain is complete it folds up to form a unique shape. This unique shape enables the proteins to do their job as enzymes, hormones or forming structures in the body such as collagen.
• Mutations occur continuously. Most do not alter the protein, or only alter it slightly so that its appearance or function is not changed.
• A few mutations code for an altered protein with a different shape. An enzyme may no longer fit the substrate binding site or a structural protein may lose its strength.
• Not all parts of DNA code for proteins. Non-coding parts of DNA can switch genes on and off, so variations in these areas of DNA may affect how genes are expressed.
• Most characteristics are a result of multiple genes interacting, rather than a single gene.
• A gamete is a sex cell that contains half the number of chromosomes than a normal cell
• A chromosome is a long, coiled DNA molecule that carries genetic information.
• A gene is a small section of DNA that codes for a specific type of protein
• An allele is an alternative version of a gene
• A dominant allele is an allele that is always expressed and is dominant over the recessive allele
• A recessive allele is an allele that is only expressed when two are present
• Homozygous is when an organism has two alleles for a particular gene that is the same
• Heterozygous is where an organism has two alleles for a particular gene that are different
• A genotype is the genetic makeup of an organism.
• A phenotype is the characteristics that you have
• When making sperm in meiosis the X and Y chromosomes are separated in the first division. There's an equal chance (50%) each sperm gets an X or a Y chromosome
• In an egg cell, the original cell had two X chromosomes so all the eggs have an X chromosome