Genetics Flashcards
what is DNA?
- a long molecule that contains a set of instructions for all cell processes
- stands for deoxyribose nucleic acid
what are the DNA bases? (4)
A-adenine
T-thymine
C-cytosine
G-guanine
what does the order of bases code?
-a message that the cell can read and certain proteins can be made
what are proteins?
-they are responsible for cell functions and characteristics that can be passed down from generation to generation
what is a gene?
-a section of DNA that contains the information to make a protein
what are chromosomes?
-long strands of tightly coiled DNA
how many chromosomes are in the human body?
- 46 total
- 2 sets of 23 chomosomes
what are pairs of chromosomes called and why?
- homologous chromosomes
- contain the same genes
how many genes per human chromosome?
-hundreds
what happens when a protein needs to be made?
-chromosome containing the gene needed unwinds to expose instructions
who is the father of genetics?
-Gregor Mendel;austrian monk
what did mendel study to determine the study of genetics?
-pea plants bc they have easily inheritable characteristics
heredity?
-passing on of traits/characteristics to offspring
genetics?
-the study of heredity
allele?
-the different versions of a gene
when is a dominant allele expressed?
-whenever present and masks or hides other alleles of the same gene
when is a recessive allele expressed?
-not expressed when dominant allele is present
how many copies do humans have from each gene?
- two copies
- one from either parent
homozygous?
- both alleles are the same
- also known as purebred or pure
heterozygous?
-when the alleles are different
genotype?
-the combination of alleles that an organism possesses
phenotype?
- the outward (physical) appearance of an organism
- does not necessarily tell which alleles an organism has for a particular trait
in the law of independent assortment…?
-no trait has anything to do with any other trait
what does the law of independent assortment work for?
-genes on different chromosomes
what does the environment play a role in?
-the expression of a genotype in a phenotype
what are the four types of inheritance?
- complete dominance
- codominance
- incomplete dominance
- sex-linked traits
what is complete dominance?
-when the dominant allele is completely dominant over the recessive allele
what is codominance?
- neither allele is dominant to each other
- both alleles are completely expressed in the hybrid
what happens when a trait has several different allele forms?
-a gene with more than two alleles is said to have multiple alleles
how many alleles does human blood have?
- 3
- allele A (equal dominance or codominance between A and B)
- allele B
- allele C (recessive to A and B)
what is incomplete dominance?
- where individuals that are heterozygous exhibit a mixture of the traits displayed by its purebred homozygous parents
- there is a blending of the traits from each of the parents to form a intermediate phenotype
what is the ration of incomplete dominance if the F1 generation crossed themselves?
-1:2:1
what is blood typing?
-a method of classifying blood based on the presence of absence of specific proteins on the surface of red blood cells
who discovered ABO blood typing?
- Karl Landsteiner, Austrian physician
- late 1800s
what was Karl Landsteiner’s discovery?
- human blood would clump up (agglutinate) in the blood vessels of the recipient animal, resulting in dealth due to lack of blood circulation
- discovered two distinct proteins that may or may not be on the surface of an individuals red blood cells (A and B)
- four blood types due to presence of absence of proteins
what are the blood types and their proteins?
- type A: A protein
- type B: B protein
- type AB: A and B proteins
- type O: no proteins
what is an antigen? (bloodtype protein)
-a substance that can stimulate (cause) an immune response in an individual
what are antibodies? and what do they do?
- substances produced by the body (Bcells) that attack antigens in an immune response
- person has specific antibodies in their blood depending on their blood type
- manufactured by immune system to attack foreign substances within the body
what are antibodies in the blood determined by?
-by the antigens (proteins) on the red blood cells
what are the antibodies of each blood type?
- type A: antiB antibodies
- type B: antiA antibodies
- type AB: no antibodies
- type O: both antiA and antiB antibodies
what happens when if a person with type A blood is given a blood transfusion of type B blood?
-antiB antibodies that are in type A blood will recognize the transfused blood cells as foreign and attack them resulting in clumping/agglutination
why is blood type O called a universal donar?
- has not proteins
- can be safely transfused into anyone
whay is blood type AB called a universal recipient?
- has no antibodies
- can receive blood transfusions of any blood type
blood type A
-who can it donate to and receive from?
- donate: A, AB
- receive: A, O
blood type B
-who can it donate to and receive from?
- donate: B, AB
- receive: B, O
blood type AB
-who can it donate to and receive from?
- donate: AB
- receive: A, B, AB, O
blood type O
-who can it donate to and receive from?
- donate: A, B, AB, O
- receive: O
how can blood type be determined in the lab?
-sample of blood placed in special blood typing tray that contains wells labels A and B
-blood has anti-serum added to it. a substance that contains antibodies in it that will react against the specific antigens on the surface of the red blood cells
blood type determined depending on which of the wells show clumping
-clumping in presense in anti A serum = blood type A
what is a sex-linked trait?
-a gene that is only found on the X chromosome and not on the Y chromosome
why do males exhibit some traits more frequently than females?
-males only need one such recessive gene to have a sex-linked trait rather than the customary two recessive genes for traits that are not sex linked.
why do males have a greater chance of having sex linked disorders?
-males only have one X chromosome
what is someone who has the genotype Ss?
- carrier
- able to pass down the s allele even if they do not have the recessive allele
how is someone a carrier for a disease?
-if the disorder is recessive and an individual is heterozygous
what are pedigrees?
-family trees that show whether family members have a certain disorder or not
what is the use of pedigrees?
-used to trace a gene as it is passes down drom one gerneration to the next generation
what do the symbols and colourings of a pedigree represent?
- squares=male
- circles=female
- shaded=has disorder
- blank=no disorder
what is the 23rd pair of chromosomes called and why?
-sex chromosomes because they determine gender
what are the 22 pairs of chromosomes called?
-autosomal chromosomes
what happens if the disorder is dominant?
-only one allele is needed for the person to have the disorder
what happens if the disorder is recessive?
-both alleles must be recessive for the person to have the disorder
when a gene affects many traits, what is this called?
-pleiotropy
albinism;albino
what is a mutation?
-change in the DNA sequence of a gene
what happens if DNA changes?
-formation of protein that has different function or a protein that doesn’t function properly
what are mutations responsible for?
- creation of genetic diversity within a population
- more genetically diverse is better able to deal with new diseases or changes in the environment
what are the types of effects of mutations? and what does the effect depend on?
- neutral
- positive
- negative
- effect depends on environment in which the organism live in
what is a neutral mutation?
- has no effect on an organisms ability to survive or reproduce
- does not affect proteins function or does affect proteins function but does not affect the ability of the organisms to survive or reproduce
what is a positive mutation?
-can enhance an organisms ability to survive or reproduce successfully
what is a negative mutation?
-can seriously impair an organisms ability to survive or reproduce successfully
what is albinism?
- albino with unability to produce melanin
- recessive trait
- lack pigment, sensitive to sunlight;high rate of skin cancer
what is melanin?
- pigment that gives skin, and hair colours
- protects skin from effects of ultraviolet light
what is hemophilia?
- mutation in gene that produces clotting factor in blood-result in inability of organism to form blood clot
- on X chromosome
what is sickle cell anemia?
- results from mutation of gene that produces hemogoblin
- defective gene changes shape of red blood cells;makes them inefficient at carrying oxygen
what is hemogoblin?
-component of red blood cells that carries oxygen
what is the negative effect of sickle cell anemia?
- ppl with 2 alleles for the defective hemogoblin develop a painful life shortening disorder called sickle cell anemia
- difficulty exercising
what is the positive effect of sickle cell anemia?
-ppl with one normal and one defective hemogoblin allele have immunity to malaria
what is malaria?
- disease carried by mosquitoes that is also painful and can be life damaging
- cant infect sickle cells
what is a mutagen?
-a factor that causes a mutation
what are the factors of mutagens? (3)
- physical
- chemical
- biological
what is a physical mutagen?
- radiation
- ionizing radiation (ultraviolet radiation) can cause chemical changes in DNA itsef
- X rays produce energy to cause mutations
what is a chemical mutagen?
-burning tobacco;releases 4000+ chemicals-known as toxins
what is a toxin?
-substances that act as poisions or have other toxic effects such as causing cancer
what is a carcinogen?
-cancer causing agents
how many carcinogens are in a cigarette?
-over 40
what is a biological mutagen?
- bacteria and viruses linked to cancer
- hepatitis B, hepatitis C viruses known to cause liver cancer
how does a virus cause a mutation?
- virus invades host cell and uses the host cell’s material to make its own DNA.
- some viruss attach their DNA to the host cell DNA, which can cause a change in the host cell DNA
