Genetics Flashcards
Mitosis
Creates two diploid cells
G1: rapid growth and cell activity
S: DNA synthesis
G2: cell prepares for division
M: mitosis
C: cytokinesis
Mitotic phase
Prophase: chromosomes coil up and take shape, centrioles move to opposite poles and send out microtubules
Metaphase: chromosomes align themselves along the equatorial plate of the cell
Anaphase: chromosomes split at the centromere and separate (spindle fibers contract) to opposite poles
Telophase: chromosomes start to uncoil and decondense, cleavage furrow forms near center of the cell, one cell becomes two
Cytokinesis: cell membrane moves inward to create two daughter cells with identical chromosomes in their nucleus
Karyotype
Look at all of your chromosomes
Meiosis
Creates four haploid cells, just mitosis twice
Gametogenesis
production of sex cells through meiosis
Spermatogenesis
-Meiosis in males
-250 million sperm a day
-occurs from puberty to death
Oogenesis
-meiosis in females
-starts before birth but pauses in meiosis 1 before the cells divide and resumes in puberty
-produces one egg and three polar bodies to support a zygote after fertilization
Congenital disorders
-clinical problems visible at birth are congenital defects
-they are caused by mutations in genes or environmental agents (alcohol abuse, viruses e.g. measles)
Nondisjunction
failure of chromosomes or tetrads to separate properly during anaphase
Down syndrome
3 copies of chromosome 21
Klinefelters syndrome
Infertile male XXY
Triple x
Infertile female XXX
Jacobs syndrome
Masculine and steric XYY
Turners syndrome
Underdeveloped female X
Gregor Mendel
Used pea plants to study genetics, heredity, and variation
Anton Van Leewenhoek
Believed that there were miniature people in sperm
19th century British theory
red plant + white plant = pink plant
Charles Darwin
offspring have variations of parental characteristics
Law of independent assortment
alleles of different genes assort independently of each other during gamete formation, so different traits are inherited independently of each other
Law of segregation
hen any individual produces gametes, the copies of a gene separate so that each gamete receives only one copy of a gene and therefore only one allele for all possible traits
Ideal ratio of alleles
9:3:3:1
Incomplete dominance
either trait is dominant or recessive, a heterozygous individual is a blend of both traits
eg. red + white = pink
Codominance
both phenotypes are expressed
eg. spotted cow
Sickle cell anemia
-decrease the ability of red blood cells to carry oxygen throughout the body.
-Blood cells become hard and irregularly shaped, they get clogged in small vessels and do not deliver oxygen to tissues.
-These people are immune to malaria
Type O blood
universal donor because it has no antigens
Type A, B and AB
have antigens for themselves
Hemophilia
condition that affects the body’s ability to produce proteins that clot blood. (x-linked recessive)
X-linked diseases
red-green colorblindness, hemophilia, x-linked severe combined immunodeficiency
Barr bodies
-inactive X chromosome
-in females only one X chromosome is functioning
Autosomal
-not x or y linked
- eg. albinism, tay sachs, cystic fibrosis
PCR
Polymerase chain reaction: an enzyme that copies DNA (archaea). It moves along the DNA and creates complementary nucleotides.
used for fingerprinting
Gel electrophoresis
clear jello with pores that DNA travels through towards the positive end to separate the sizes of DNA
Friedrich Miescher
isolated nuclein (RNA and DNA) from nucleus
Phoebe Levine
identified four bases of DNA
Linus Pauling
chromosomes were hereditary material
Frederick Griffith
experiments on pneumonia by heat-treating and killed them
Oswald Avery
discovered nucleic acids exchanging
Chargaffs Rule
always have Adenine and Thymine at the same ratio, and Cytosine and Guanine
Rosalind Franklin
x-ray crystallography, photographed first double helix
James Watson and Francis Crick
Stole Franklins photo
RNA
has uracil and adenine (instead of thymine)
Nitrogenous bases
Pyrimidines: cytosine, uracil, thymine
Purines: adenine, guanine
DNA vs RNA
DNA has one more oxygen
Nucleotide contains
-phosphate group
-5-carbon sugar (ribose and deoxyribose)
-nitrogenous base (pyrimidines and purines)
Structure of DNA
Backbone: phosphates and deoxyribose sugar
Teeth: nitrogenous bases
Thymine and cytosine
-one ring of carbon and nitrogen atoms
-TWO HYDROGEN BONDS
Adenosine Triphosphate
what the mitochondria makes
Adenine and guanine
-two rings of carbon and nitrogen atoms (guanine GOT the oxygen)
-THREE HYDROGEN BONDS
Types of chromosomal mutations
- Deletion (missing a section)
- Duplication (copy a section twice)
- Inversion (DNA put back in backwards)
- Translocation (moved to different spot on chromosome)
- Nondisjunction
Point mutation
Affects a single base pair by substitution from another
1. Nonsense mutations: code for a stop that can translate the protein
2. Missense mutations: code for a different amino acid
3. Silent mutations: code for the same amino acid
Frameshift mutation
Entire code shifts forward or backward. (genes are read in threes)
1. Insert a new nucleotide into the chain
2. Remove one nucleotide into the chain (forwards)
Causes of mutations
Physical: radiation from UV rays, x-rays, or extreme heat
Chemical: molecules misplace base pairs or disrupt helical shape of DNA, drugs
