Genetics: Quiz 1 Flashcards
Define genetics
Study of hereditary and variation of inherited characteristics
Define DNA
stores hereditary info in organisms
Define Chromatin
Term used to describe genetic material during interphase. Long stretched out strand of DNA in nucleus with all its proteins
Define Gene
Segment of DNA that encodes for a specific piece of information/trait
Define Diploid cell
Cells that have 2 copies of each chromosome
Define haploid cell
Cells that have half the number of chromosomes
Define homologous chromosomes
Chromosomes that code for the same info and are the same size. Not genetically identical.
Define chromatid
A single “arm” in a duplicated chromosome
Define sister chromatid
The 2 chromatids it a duplicated chromosome that are attached together at their centromere. Genetically identical.
Explain Interphase
Period between cell divisions where cell undergoes normal activities (obtaining energy products, synthesizing, repairing damage)
G1 - (gap 1) cell does normal cell things and preps for S phase
S - (synthesis phase) DNA is replicated for cell division
G2 - (gap 2) cell begins final prep for cell division
Explain mitosis
Cell division
Prophase- chromatins condense, nuclear membrane dissolves
Metaphase- spindle fibres guise chromosomes into middle of cell
Anaphase- spindle fibres pull sisters apart and pull cell to make cell bigger
Telophase- chromosomes uncoil, fibres dissolve, nuclear membrane forms.
Why do some cells undergo division faster?
- different stages of life (childhood)
- cancer cells
- genetics
- some cells have shorter lives and need to reproduce faster
Define meiosis
Division of the nucleus in sex cells.
What is a tetrad?
A pair of homologous chromosomes, each with 2 sister chromatids
What is crossing over?
The exchange of chromosome segments between homologous pairs during SYNAPSIS (physical pairing of homologous genes during prophase 1)
What is synapsis?
Physical pairing of homologous chromosomes in prophase 1
What is independent assortment?
Random distribution of a chromosome to a daughter cell depending on how chromosome alone up in metaphase 1 and 2
Meiosis occours in this type of cell
Gametes
Mitosis occurs in this type of cell
Somatic
What is non disjunction?
The failure of homologous chromosomes to move to opposite poles of the cell during meiosis; results in an abnormal number of chromosomes in daughter cells
What types of non disjunction are there?
TRISOMY - The gain of 1 extra chromosome (3 in place of 1 homologous pair)
MONOSOMY - the loss of 1 chromosome (one 1 copy where there should be a homologous pair)
What is trisomy?
The gain of 1 extra chromosome (3 in place of 1 homologous pair)
What is monosomy?
the loss of 1 chromosome (one 1 copy where there should be a homologous pair)
Explain chromosomal errors
Deletions - sections of DNA are missing
Duplications - sections of DNA are duplicated
Inversions - sections of DNA are copied in reverse order
Translocations - sections of DNA are reattached to the wrong chromosome (non-homologous)
What is a karyotype?
Photographic inventory of an individuals chromosomes, usually taken in late prophase or metaphase
Define allele
Each genes possible different forms. Ex. Gene is hair colour and allele could be red, blonde or brown
What are the 2 types of alleles?
Dominant (capitol letter)
- always represented in physical characteristics of present
Recessive (lower case)
- only represented if there do dominant allele
Define homozygous
An individual in which both alleles are the same.
Homozygous dominant - BB
Homozygous recessive - bb
Define heterozygous
Hybrid
An individual in which both alleles are different.
Heterozygous - Bb
Define genotype
Genetic make-up of the individual (BB/Bb/bb)
Define Phenotype
Physical appearance of the individual
Define Down Syndrome
- trisomy of 21
- developmental and intellectual disabilities
Define Turner Syndrome
- 1X/missing X
- don’t reach sexual maturity
Define Klinefelter Syndrome
- 2X, 1Y
- exhibit some female body characteristics
Define Patau Syndrome
- trisomy of 13
- major developmental issues
- often only live a few months
Define Edwards Syndrome
- trisomy of 18
- most fetuses die before birth
- many organ systems defective
