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60 Cards in this Set
- Front
- Back
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GENETICS
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tHE BRANCE OF BIOLOGY THAT STUDIES THE WAYS IN WHICH HEREDITARY INFORMATION IS PASSED ON FROM PARENTS TO OFFSPRING
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GENE
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A segment of DNA that helps control a specific hereditary trait such as eye color
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HEREDITARY
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Genetic material passed on from parents which determines the characteristics of an individual (50% comes from each parent)
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How many chromosomes are in humans?
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46 chromosomes in humans ensure all charcteristics of the species
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What are pigments?
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Proteins
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The basic idea of genetics
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Each body cell of an organism has two copies of a gene for each trait.
One copy is at the some position on each chromosome of a homologous pair. The 2 genes may or may not be of the same form, since one came from mom and one came from dad |
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ALLELES
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Different copies or forms of a gene controlling for a certain trait, such aas tall vs short
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HOMOZYGOUS
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When both genes for that trait are of the same form, such as having two allels for tallness
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HETEROZYGOUS
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When the genes for that trait are of differnt forms, such as having one allele for tallness an done allele for shortness
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DOMINANT ALLELE
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The one that is expressed in a heterozygote
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RECESSIVE ALLELE
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The one that is not expressed in a heterozygote
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GENOTYPE
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The combination of alleles
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PHENOTYPE
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The physical expression of the genotype
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LAW OF DOMINANCE
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an organism that is a hybrid for a pair o contrasting traits will express the dominant phenotype.
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LAW OF SEGREGATION
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Factors that occur in pairs are seperated from eachother during gamete formation and recombine at fertilization
An offspring may express a phenotype different from eother parent though inheritance of unexpressed recessive alleles. |
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Mendel worked with....
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pea plants because they are easy to grow/ mature quickly/ have sharp contrasting traits/ can be cross-pollinated
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7 trats Mendel studied
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Shape
color coat color pod color pod shape stem length flower position |
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CROSS POLLINATION
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Cross parents with contrastinc traits
Results in certain % of offspring displaying each phenotype |
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GENERATIONS
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Parent (P)
First Filial (F1) Second Filial (F2) |
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GENE CHROMOSOME THEORY
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Mendel's work rediscovered around 1900
Sutton suggested that the "factors" referred to by Mendel are carried by homologous chromsomes |
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LAW OF PROBABILITY
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If there are several possible events that might happen, and no one of them is more likely to happen than any other, then they will all happen in equal numbers.
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PUNNET SQUARE
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A diagram shwoing the results likely from any cross
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MONOHYBRIDS
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2 pure recessive
2 pure dominant 1 pure dom. 1 pure rec. |
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DIHYBRIDS
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Follow 2 pairs of contrasting traits simultaneously
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LAW OF INDEPENDENT ASSORTMENT
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Differnet traits are inherited of each other
Genes for different traits are separated and distributed to gametes independently of each other DETERMIND DURING METAPHASE I OF MEIOSIS |
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IMCOMPLETE DOMINANCE
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A separate phenotype exists for the hybrid
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CODOMINANCE
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2 dominant alleles are simultaneously expressed
(hybrid is a blend of the dom. and rec.) |
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MULTIPLE ALLELES
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There are more than 2 possible alleles (blood type)
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SEX-LINKED INHERITANCE
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AUTOSOMES-22 pairs of chromosomes whcih code for the same traits in humans
SEX CHROMOSOMES- 1 pair varies between males and females (XY and XX) --> male determines sex |
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GENE LINKAGE
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If a genes are found on the same chromosomes they are inherited as a linkage group
Can be separated only by crossing over in prophase I of meiosis |
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POLYGENIC INGERITENCE
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2 or more genes can affect a single chromosome (multiple gene ingeritence)--> done as dihybrid
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GENE EXPRESSION
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Gnes control protein synthesis
The "one gene, onepolypeptide" rule states that the synthesis of each polypeptide is controlled bya differnt gene |
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Each gne directs the synthesis of a particular polypeptide
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Genes (are) DNA (and when) Transcripted (become) RNA (Then after) Tanslation (They make) Protein (and when) expressed (it is a) Trait
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MUTATIONS
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Genetic material represents volumes of information which has been copied and recopied millions of times. It is not surprising that mistakes ocasionally occur. these mistakes are called mutations
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A mutation is a sudden change in the structure or amount of genetic material
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Some are harmful
Some have no effect Some are beneficial and provide variation which allows organisms to adapt to their environment |
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Causes of mutations
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-Not all causes are known
-Many results form random errors in DNA replication -Environmental factors called mutagens (ex.radiation) -To be inherited, it must occur to the DNA of a gamete -Mutatsion in somatic cells are not transmitted to offspring |
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CHROMOSOMAL MUTATIONS
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An abnormal change in the structure of all or part of a chromosome, or in the number of chromosomes
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Changes in chromosome structure
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-takes place during meiosis
-chromatisd become tangled and rearranged -not to be confused with crossing over |
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Nondisjuction
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-the addition or loss of an entire chromosome
-chromosome that normall separate during meiosis remain together -causes a variety of genetic disorders, indluding Down's Syndrome (+1) Turner's Syndrom (-1) Klinefelters syndrome (XXY) |
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POLYPLOIDY
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-celsl contain a multiple of the normal number of chromosomes
-chromosomes do not separate normally during meiosis or mitosis -common in plants resulting in larger size but possible sterility |
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GENE MUTATIONS
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A change that affects a gene on a chromosome. Since genes specify tghe order of amino acids in polypeptide chains for specific proteins, changes in the sequence result in changes of the message transcribed during DNA transcription
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GENERAL STATISTICS
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-mutatsions occur randomly in all cells
-muated somatic cells usually die and leave no impact -mutated sex cells cause the offspring to have the mutation in all of its cells |
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POINT MUTATION
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-only a sungle nucleotide in a ene has been cahnged
-all triplets beyond that are altered -usually renders the gene useless -organism lacks proteins specified by the gene -cause of many inherited diseases |
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SUBSTITUTION
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-a single base in a DNA nucleotide is substituted for another
-changes one mRNA codon and one amino acid in a protein -may result in an abnormally functioning protein |
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Sex-linked disorders
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-abnormalities passed down through the X chromosome
-ex. hemophilia |
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Autosomal Disorders
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-abnormalities cause by recessive defective alleles
-rarely a problem because the cominant gene will cancel it out if present -few dominantt defective alleles exist |
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DETECTING GENETIC DISORDERS
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People who carry a genetic disorder can be tested and counseled before having children in order to assess the risks of having a child with an inherited disorder
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BREEDING
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mating of organisms with the most desirably traits
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CLONING
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the production of organisms which normall reproduce sexually
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Plant cloning
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-simple compared to animal cloning
-a cell from a living organism is placed in a special growing medium -the single cell will develop into a complete organism identical to the one it came from |
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Animal cloning
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Since all body cells of an organism contain the same bumber of chromosomes, theoretically any one should be able to be developed into an identical organism
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Process of cloning
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-haploid nucleus of egg cell replaced with diploid nucleus of body cell
-egg cell with replaced nucleus develops into complete individual -clone has genes identical to those from transplanted nucleus |
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Difficulties with animal cloning
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-adult cells have many genes which are turned off, or inactive due to cell type
-a nucleus from a cell in the early blastula stage work |
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Amniocentesis
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draw fluid fomr amniotic sac and run tests
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Karyotype
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take picures of cell during netosis and look for abnormalities among chromosomes
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GENE SPLICING
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Involves changing a cell's DNA by breaking it open, inserting a new piece, and closing
**Organisms with goreign DNA inserted are cloned and screened to determine which have actually obtained the deired gene. The entire process is much more comples than made out to be here. |
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GENE THERAPY
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-use of gene splicing to correct genetic defectsby transferring normal genes to cells that lack them
-still in experimental stages |
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Benefits of genetic engineering
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-produce large amounts of previously rare substances (insulin 4 diabetes, cltting substances 4 hemophilia)
-Produced plants which are resistant to disease, insects, or weed-killing substance -produce cows which produce more mild or fatter livestock through growth-promoting hormones |
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safety issues of genetic engineering
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-production of new microorganisms could accidentally result in a new disease
-until we try on humans we cannot know the effect on humans -to reduce risks, compliance with federal rules and safeguards is required for unstitutions partaking in this type of research (side-effects could hardm organism involved) |
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ALL
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DONE
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