Genetics Flashcards
What is DNA?
Deoxyribonucleic acid, it is located in the nucleus, this is what contains genetic information
What is RNA?
Ribonucleic acid there are 3 types:
mRNA
tRNA
rRNA
What are A, T, C, and G and what do they stand for / match up with
Adenine Thymine Cytosine Guanine C with G A with T
What are purines?
Part of the DNA structure, they have a double ring structure
What are pyrimidines?
Part of the DNA structure, they have a single ring structure
What are nitrogenous bases connected by?
Hydrogen bonds
Which way do DNA strands run?
Anti-parallel
What is a nucleotide?
part of the DNA structure, they are made of sugar, they are bonded by a phosphate bond & nitrogen bond
What is a gene?
Section of DNA responsible for inheriting particular characteristics
What are the 2 main parts of the cell cycle?
Interphase and mitosis
What is Mitosis?
Cell division that results in the production of 2 identical daughter cells
What are the stages of mitosis? (4)
- Prophase: chromatin coils to form visible chromosomes
- Metaphase: chromosomes move to the equator of the cell
- Anaphase: the centromeres split and sister chromatids are pulled apart to to the opposite poles of the cells
- Telophase: two daughter cells are formed and the cells divide
What is Meiosis?
produces reproductive cells called gametes (egg and sperm) essentially mitosis twice
What are gametes?
Egg and sperm cells (reproductive) they are haploid (n), they contain 1/2 the number of chromosomes (eg there are 46 in humans so their would be 23 in each haploid)
What are the stages of meiosis I?
Prophase I: nucleur membrane and nucleolus disappear and spindle fibres form, similar chromosomes match up (homologous chromosomes) - made up of 4 chromatid known as tetrad
Metaphase I: the pairs of chromosomes line up along the equator randomly (independent assortment) this is synapsis
Anaphase I: the homologous chromosomes separate and move to opposite poles, this is disjunction
Telophase I: the spindle disappears, nuclear membrane reforms, cytokinesis occurs,
What are the stages of Meiosis II?
identical to mitotic cell division (PMAT)
What is the end result of meiosis?
4 non-identical daughter cells, meiosis I has a diploid of chromosomes (46), meiosis II has a haploid set of chromosomes (23) GAMETOGENESIS (the production of gametes)
Male gametes
produced by spermatogenesis, the sperm only have a nucleus and flagellum
Female gametes
produced by oogenesis: only one cell becomes a viable sex cell
What is genetic variation?
- during prophase I the tips of non-sister chromatids may cross over during synapsis and exchange genetic information
- during metaphase I homologous chromosomes independently assort to form tetrads
Genetics
the scientific study of inheritance
Heredity
the transmission of characteristics from one generation to the next
Allele
the particular DNA form that appears at the gene location for an inherited characteristic
Homologous chromosomes
pairs of chromosomes that carry corresponding DNA codes (1 from mom, 1 from dad)
Homozygous
refers to an offspring that receives 2 identical alleles for a given gene location
Who was Gregor Mendel?
“Father of genetics”
What is the principle of segregation?
when an allele from a parent sorts into a separate gamete
what is a dominant trait?
when a characteristic is always expressed, or always appears in an individual
what is a recessive trait?
when a characteristic is present, but may not be expressed except in homozygous form
What is the law of dominance?
if an organism is heterozygous one trait will always be dominant
What is the law of independent assortment?
offspring can have new combinations of genes that were not present in the parents
What is incomplete dominance?
when both alleles contribute to the phenotype of the heterozygous individual, aka blending inheritance. Neither of the alleles hides the presence (think white + red makes pink)
What is codominance?
two alleles are expressed at the same time capital letters with superscripts are used to demonstrate this (think roan colour in cattle)
What are multiple alleles?
eg. of codominance and dominant / recessive genetics, there are more than 2 possible alleles.
What are the rules of bloodtypes?
I^A and I^B are dominant to i
I^A and I^B are codominant to eachother
ii is recessive
What is polygenetic inheritance?
is controlled by 2 or more genes, each with 2 alleles, so there is a wide variation eg. skin and eye colour
What are lethal genes?
they are alleles that can lead to the death of the organism, may be dominant or recessive, they control more then 1 phenotype
What are autosomal chromosomes?
22 of the 23 pairs of chromosomes that aren’t related to gender
What are sex chromosomes?
the last pair of chromosomes responsible for determining the gender of the offspring, x is girl, y is boy
What is a karyotype?
diagram or photograph of somatic chromosomes
What are the rules of a pedigree?
men are square
women are circle
people showing a characteristic are solid colour
women who are carriers have half of the circle shaded in
Genetic mutations
an error in the DNA sequence
may also be seen at the chromosomal level
What are the chromosomal mutations? (4)
- delection - a portion of chromosome is lost
- Duplication - a portion of the chromosome is added
- inversion - a portion of the chromosome is inverted
- translocation - a portion of the chromosome is switched with another
