Inheritance, Variation and Evolution Flashcards
9+10 =
21
What is DNA?
Deoxyribonucleic acid is a chemical that all the genetic material in a cell is made from. It contains coded information for all the instructions to put an organism together and make it work. DNA determines what protein the cell produces and in turn what type of cell.
Where is DNA found?
DNA is found in the nucleus of cels in really long structures called chromosomes. Chromosomes come in pairs.
Describe the structure of DNA
It is a polymer made of two stands coiled together to form a double helix.
What is a gene?
A gene is a small section of DNA found on a chromosome.Each gene codes for a particular sequence of amino acids which are put together to make a protein. Genes have the instructions to tell cells which order to put amino acids.
What is a genome?
It is the entire set of genetic material in an organism
What does the exploration of genomes do for humanity?
It allows scientists to identify genes linked to different diseases. Understand inherited diseases and develop effective treatment. The genome can be used to understand migration and the history of ancestors.
What is a nucleotide?
They are the repeating unit in the DNA polymer they are made of a sugar molecule, one phosphate molecule and one base. The sugar and phosphate molecule form the backbone of the DNA strands, these molecules alternate through the stand. One of four bases links with a sugar molecule.
What are base pairs?
The base pairs are what decides the order of amino acids in a protein they make up a gene. They are always complementary paired A pairs with T and C pairs with G.
Where are proteins made?
In the cytoplasm by ribosomes.
What is mRNA?
DNA in the nucleus is too large to leave the nucleus so mRNA is used to get the code from the DNA to the ribosome which is outside the nucleus.
Give three examples of proteins that can be formed in protein synthesis
Enzymes
Hormones
Structural proteins
What is a mutation?
Any random change in the organisms DNA, they can sometimes be inherited. Mutations change the sequence of the DNA bases in a gene which produces a genetic variant. Some mutations lead to a change in the protein it codes for.
What could increase the chance of a mutation?
Exposure to radiation or certain substances
How can a mutation be dangerous to your body?
In some cases the mutation can drastically change the protein it is suppose to code for, for example an enzyme if due to the mutation the enzymes active site was to change it can no longer bind to the substrate. Also structured proteins such as collagen could lose their strength making them useless.
What is an insertion?
It is a type of mutation where a base is inserted into the DNA base sequence where it shouldn’t be, an insertion changes the way the three bases are read which can change the amino acid they code for. Insertion mutation can change more than one amino acid as they can have a knock on effect on the base further on in the sequence.
What is deletion?
This is a mutation where a random base is deleted from the DNA base sequence. They change the way the base is read and have a knock on effect.
What is substitution?
This is a mutation where a base pair is randomly changed, this has no knock on effect to other bases in that gene.
What is sexual reproduction?
This is where genetic information from two organisms combine to produce an offspring. The mother and father both produce gametes through meiosis e.g. egg and sperm cells (LOL). Each gamete will contain 23 chromosomes, these two cells fuse together to form a cell with the full number of chromosomes.
What is variation?
This is the mixture of genetic information to achieve an offspring with different genetic code to the parenting DNA.
What is plant sperm?
Pollen
Describe asexual reproduction?
This is where there is only one parent so the offspring is genetically identical. This happens by mitosis and is called a clone. For example bacteria, some plants, some animals
Describe meiosis
The genetic information is copied, the chromosomes duplicate.
The chromosomes line up in the centre of the cell they are pulled apart by spindle fibres then the cell membrane pinches the middle and the cell splits.
The cell then splits a second time using the same process except the genetic information does not duplicate.
The chromosomes are pulled apart so each cell (gamete) has one set of chromosomes.
What is a gamete?
A mature haploid male or female germ cell which is able to unite with another of the opposite sex in sexual reproduction to form a zygote
What happens after the gametes have fused after fertilisation?
The resulting new cell divides by mitosis to make a copy of itself . This repeats many times to produce lots of new cells in an embryo. As the embryo develops these cells start to differentiate into the different types of specialised cells that make up a whole organism.
Give some examples of organisms that can reproduce asexually and sexually.
Malaria-this is a parasite that reproduces sexually in the mosquito but asexually in a human
Fungi
Plants-production of seeds sexually but also asexually.
How many pairs of chromosomes do you have?
23
What does the 23 pair of chromosomes control?
Your sex
What distinguishes a male and female in their chromosomes?
xy as the 23rd pair - male
xx - female
What are alleles?
They are versions of genes, alleles are responsible for determining characteristics in the body such as hair colour, only the dominant allele will control the characteristic.
What is a genotype?
The combination of alleles you have.
What is a phenotype?
This is the molecular level of how your characteristics are determined.
What is the definition of homozygous?
It is an organism has two alleles for a particular gene that are the same.