Genetics Flashcards
Genes
unit of genetic material, a defined portion of chromosomes that encodes for a particular trait or substance such as hair color, blood type, etc.
Alleles
the different forms a particular gene can occur in (brown, green, blue)- you have two copies of each gene (one from mom and one from dad) so there are two potential alleles for each
homozygous
2 identical alleles for a particular gene
heterozygous
2 different alleles for a particular gene
Dominance
will always be expressed, indicated by a capital letter
Recessive
will be masked by a dominant gene, can only be expressed if there is no dominant gene present- indicated by a lower case letter
Codominant
Incomplete dominant
neither masks the other so both are expressed (AB blood type)
Incomplete dominance- the traits blend (pink, RW, RR red, WW, white)
Genotype
the makeup of the genes, which 2 alleles are present
phenotype
what actually gets expressed-what you “see”
Monohybrid cross of dominant or recessive traits
mom brown eyes-Bb
dad blue eyes-bb
mom brown eyes-Bb
dad brown eyes-Bb
50% blue eyes (bb)
50% brown eyes (Bb)
75% brown eyes- BB or Bb
25% blue eyes- bb
dihybrid cross
two traits, four results or phenotypes will be seen
Blood Types
are based on what is on the cell surface
Type A- A antigen on red blood cell’s (RBCs) surface
Type B- B antigen on the surface
Type AB- both A and B antigens on the surface
Type O- neither A or B antigen on the surface
genetics of blood types
O is recessive, must be homozygous (OO)
A is dominant, can be AA or AO
B is dominant, can be BB or BO
AB is codominant
Blood Donation/transfusion
Type A-makes antibodies against B, can receive from A or O
Type B- makes antibodies against A, can receive from B or O
Type AB- can receive from everyone (A, B, or O)
Type O- makes antibodies against A and B, can only receive from O, but is a universal donor
Rh disease
Rh+ is dominant
Rh- is recessive
a situation where Rh- mother is carrying an Rh+ child. After she is exposed to Rh+ RBCs during the first pregnancy, she may produce IgG antibodies which will cross the placenta and attack fetal RBCs in later pregnancies
hemolytic disease of the newborn
X chromosomes disease
generally affects males since they only have on X chromosome, the second X chromosome is always a good back up for females
Hemophilia- x-linked disorder, recessive, defect in blood clotting protein
Color blindness
Autosomal Recessive disorders
2 copies of the bad gene in order for it to be expressed Albinism Sickle cell anemia PKU Cystic fibrosis
Albinism
a defect in the production of melanin
Sickle Cell Anemia
single amino acid change in the gene that makes hemoglobin, RBCs have sickle shape
PKU
Phenylketonuria-enzyme defects leads to the build-up of phenylalanine in the bloodstream and neurological problems
cystic fibrosis
enzyme defect causes the production of abnormal mucus that cause problems in the respiratory and gastrointestinal tract
Chromosomal and structural disorders
physical or structural defects in the chromosomes rather than in the genes, often from nondisjunction- where one or more chromosomes pairs do not separate during mitosis or meiosis
Trisomy/Polyplodiys- an unusual amount of a particular chromosome
Ex: down syndrome (aka trisomy 21), XXY or XYY extra copy of a chromosome
Monosomy/anuplodiy- one copy of a chromosome, just an X, example: Turner’s syndrome
Replication fork
the initial step is the splitting the two strands to form a replication fork- it involves the helicase enzymes
DNA polymerase-
synthesis the DNA complementary strand
