Genetics Cheat Sheet (DRAFT) by holmesan123

Cells are the basic units of all living things including human beings. Cells aren’t all exactly the same in shape but their structure is similar. New cells are produced from existing cells.

Cell membrane (Gate of the cell) - Holds and filters everything in and out of the cell

Mitoch­ondria (Power­house of the cell) - Produces the energy for the cell

Nuclear membrane (Gate of the nucleus) like the cell membrane, it protects and filters the nucleus.

Mitosis Cells divide by the process of mitosis for growth and to replace worn out or injured cells. Mitosis produces two Geneti­cally identical daughter cells to the parent cell so that the same cell functions and processes can continue.

Gametes Human - sperm (male) egg (female) Plants - pollen and ovule Human body cells (somatic cells) contains 46 chromo­somes. This is known as the Diploid number. Gametes produced in meiosis have half the diploid number of chromo­somes known as the Haploid number. When the ovum and sperm fuse in fertil­isa­tion, the diploid number of chromo­somes is restored in the zygote. If cells didn’t divide you wouldn’t grow. Mitosis makes identical cells.

Chromo­somes and their genes are made up of a molecule called DNA. Each chromosome is a very long section of tightly coiled DNA. DNA molecules create the code that controls what your cells are and what they do.

Base pairs hold the strands of the DNA helix together. Each different nucleotide has a letter, either A, T, C, or G, which is determined by the nitrogen base it has.

A always pairs with T. You can remember this because the straight letters go together. C always pairs with G. You can remember this because the curved letters go together.

Proteins are long molecules made from chemical units called amino acids. The code for the amino acids in from the genetic code, these amino acids come together to create the protein. Genes contain the instru­ctions to make the proteins. Each amino acid is coded for by its on special sequence of threes bases called a triplet.

Inside the nucleus are chromo­somes. Chromo­somes are long sections of DNA (Deoxy­rib­onu­cleic acid).

Different species have different numbers of chromo­somes. Humans have 46. We receive 23 from each of our parents, which are carried by the egg and sperm.

The dominant allele is always expressed in the phenotype when present in the genotype, it masks the presence of the recessive allele.

Two dominant - dominant expressed One dominant and one recessive - dominant expressed Two recessive - recessive expressed

Alleles are the different forms of a gene. For each charac­ter­istic you have two alleles. One from your biological father and one from your biological mother.

Phenotype The phenotype is a set of charac­ter­istics that you can see of a person. They are formed by the genotype and the enviro­nment.

Hetero­zygous Where two different alleles are present in the genotype for a particular gene. One is dominant and one is recessive.

Proteins are long molecules made from chemical units called amino acids. The code for the amino acids in from the genetic code, these amino acids come together to create the protein. Genes contain the instru­ctions to make the proteins. Each amino acid is coded for by its on special sequence of threes bases called a triplet.