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genetics definitions (genetics- is the study of what organisms are made of)
genetics definitions
genetics- is the study of what organisms are made of
definitions:
gene
= a gene is section of DNA that codes for a protein and therefor a characteristic
DNA
= a very long molecule that is made up of nucleotides. carries instructions to the next generation and determines the phenotype (deoxyribo/se nucleic acid)
Alleles
= alternate forms of a gene. ( they code for same characteristics althouhg have a slighyl iffernet order of bas
sexual reproduction
= reproduction involving two parents, where the offspring is composed of one parental strand and one newly made strand
homozygous
= two alleles that are the same for a particular trait
heterozygous
= two alleses that are different for a particlar trait
diploid
= cell with the full set of chromosomes (in humans its 46)
pure breeding
= individuals that are homozygous- they will always offspring with the same genotype ( and phenotype) if they are bread together
haploid
= having only a single set of chromosomes (n). half the full set of chromosomes- for humans this is 23
asexual reproduction
= reproduction involving only one parent producing identical offspring (there is no variation in asexual reproduction except from mutations)
chromosome
= threadlike structure of DNA and protein found in the nucleus of cells- carries genetic information in the form of genes
bases
= Adenine, Thymine, Cytosine, Guanine (base paring rule = A&T + C&G - visa versa)
dominent
= alleses witch are always expressed in phenotype even if only one is present in the genotype, written with a upper-case letter
karyotype
= photograph of an individuals chromosomes out out and arranges according to their size
double helix
= the twisted ladder shape of DNA
fertilization
= the joining of male and female gametes. it is a random event and helps to create variation
gametes
= reproductive cells that contain half the number of chromosomes compared to the parent cell
genotype
= the particular alleles of an organism (e.g. Tt)
phenotype
= the observable characteristics of an individual resulting from its genotype
mutation
= a change in the base sequence of DNA (if the mutation occurs in a body cell, it will not be passed on)
meiosis
= cell division in testes and ovaries producing 4 new cells ( gametes) - genetically different to each other, and to the parent cell. the gametes are haploid cells (only have half the genetic information for the parents)
mitosis
= cell division body cells for growth and repair - produces 2 new cells genetically identical to each other and to the parent cells are diploid cells ( have the full set of genetic information)
natural selection
= when orgnism with a survival advantage are more likely to survive, reproduse and pass on their genetic information. causes variation within a population and is the reason for evolution
mono hybrid cross
= punnet square = a chart that shows possible combinations of alleles that can result in a genetic cross
nucleotide
= forms the basic structural unit of DNA, composes of sugar molecule, a phosphate group, and a base (A,T,C,G)
pedigree chart
= diagram/family tree that shows the phenotype of related individuals
punnet square
= a chart that shows all the possible combinations of alleles that can result from a genetic cross
pure breeding
= individuals that are homozygous - will always produce the same offspring when crossed together
deoxyribose (sugar)
= molecule that alternates withe the phosphate to make the upright of DNA
phosphate
= molecule that alternates with the sugar to make the uprights of DNA
triplet code
= each triplet codes for a different amino acid that goes into forming a the protein (it is a chain of triplet codes) the triplet code is 3 bases in the DNA
zygote
= a fertilized egg/ovum that contains the full set of chromosome (diploid cells). will continue to grow into a baby
variation
= difference between organisms within a population - cam be continuous or discontinuous depending of weather the variation (mutation) occurs in the body or sex cells.
nucleus
= cell part that contains chromosomes (+ control center of the cell)
ressesive
= allele witch is only expressed when two of them are present in the genotype, written as a lower case letter.
test cross
= way to test genotype of an organism who's phenotype is known
The concept of hereditary:
'many' Features are inherited from our parents. each parent contributes half of the offsprings genetic makeup. - resemblance occurs when one parents contribution is expressed over the other parents