Genetics Flashcards
What is genetics?
Genetics is the field of biology that involves the study of heredity and variation of living organisms and how genetic information is passed from one generation to the next.
What does the cell theory state?
- all living things are composed of one of more cells
- cells are the smallest units of living organisms
- new cells come only from pre-existing cells
What is the first stage of the cell cycle? What happens?
Interphase
-cell carries out normal functions, grows, makes copies of its genetic material to prepare for mitosis
What is the second stage of the cell cycle? What happens
Mitosis: cell nucleus and genetic material divides
PMAT
What happens during prophase?
-cell’s chromatin condenses into chromosomes
What happens during metaphase?
-spindle fibres from opposite poles attach to the centromere of each chromosome, guiding the chromosomes to the equator of the cell
What happens during anaphase?
-each centromere splits apart and the sister chromatids separate from each other
What happens during telophase?
- the chromosomes start to unwind into strands of chromatin
- the spindle fibres break down
- the nuclear membrane forms around the new set of chromosomes and a nucleolus forms within each new nucleus
What happens during cytokinesis?
-divison of cell cytoplasm and creation of new cell
What is DNA?
- stands deoxyribonucleic acid and DNA is how traits are passed onto new cells (genetic makeup)
- Adenine, guanine, thymine, cytosine
What is a nucleotide?
-the individual units of each strand of DNA
Phosphate, sugar and base (Adenine-Thymine, Guanine-Cytosine)
What is mitosis?
-stage where cell division occurs to create a new cell
What is meiosis?
-the process of cell division that produces haploid cells
What are the differences between mitosis and meiosis?
Mitosis
- 2 identical daughter cells
- daughter cells are identical to parent cells
- 4 phases
- crossing over does not occur
- chromosome pairs line up
- somatic (body) cells produced
Meiosis
- female: 1 egg and 3 polar bodies
male: 4 sperm - daughter cells are not identical to parent cells
- 8 phases
- crossing over can occur
- chromosome pairs line up
- sex cells produced
What is independent assortment?
- happens in metaphase 1
- how the chromosomes line up is what decides the variation in diploid offspring of the haploid cells
What is crossing over?
- happens during synapsis of prophase 1
- the exchange of chromosomal segments between a pair of homologous chromosomes
What is recombination?
-recombining the maternal and paternal chromosomes so that new forms are created (this is variation in the creation of gametes)
What is deletion?
-when a piece of chromosome is deleted
What is duplication?
-when a section of chromosome appears two or more times in a row
What is inversion?
-when a section of a chromosome is inverted
What is translocation?
-when a segment of one chromosome becomes attached to a different chromosome
What is the law of segregation?
-traits are determined by pairs of alleles that segregate during meiosis so that each gamete receives one allele
What is a dominant allele?
-always appears when an individual has an allele for it
What is a recessive allele?
-only appears when an individual has two alleles for it
What is a genotype?
-the combination of alleles for any given trait or an organism’s entire genetic makeup
What is a phenotype?
The physical and physiological traits of an organism
What would you need to cross to get a 3:1 ratio?
HH x hh (homozygous dominant with heterzygous)
What would you need to cross to get a 9:3:3:1 ratio?
HhMm x HhMm
Homozygous dominant vs homozygous recessive?
HH and hh
What is the difference between mono hybrid and dihybrid?
Monohybrid: homozygous/heterozygous dominant or homozygous recessive
Dihybrid: same as monohybrid but with 2 traits
What is the law of independent assortment?
-during gamete formation, the two alleles for one gene segregate or assort independently of the alleles for the other genes.
This means that there are many different variations of an offspring because the genes mix and match.
What is autosomal inheritance?
-the inheritance of traits determined by genes on the autosomal chromosomes (1-22 in humans)
What is autosomal dominant?
-the inheritance of a dominant phenotype whose gene is on an autosomal chromosome (1 copy of allele is needed)
What is autosomal recessive?
-the inheritance of recessive phenotype whose gene is on an autosomal chromosome (must have 2 copies of allele)
What is incomplete dominance?
Neither of the two alleles for a gene can completely conceal each other (red + white flower = pink flower)
What is co dominance?
Both alleles are fully expressed (red roan horses)
