chapter 3 Flashcards
mitochondrial dna (mtDNA)
- contains 37 genes
- inherited by mother’s mtDNA
- matriline (mother’s lineage) of mtDNA can be traced back hundreds of thousands of years
- it can differ among different parts of a person’s body
replication
- how dna reproduces itself
- takes place in the nucleus
- DNA makes identical copies of itself, going from one double-stranded parent molecule of DNA to two double strands of daughter DNA
how does DNA replication connect with human variation
- errors can occur during replication, leading to mutations which cause variation
- natural selection
mitosis
- single cell (zygote) replicates itself millions of times
- production of identical daughter cells from an original parent cell involves one DNA replication followed by ONE cell division
- in the cell division, a diploid cell (organisms have a full set of chromosomes) divides to produce two cells (also diploid)
meiosis
- involves ONE DNA replication and TWO cell divisions
- gametes only have half the chromosomes that are in somatic cells (haploid)
- contains one chromosomes from each pair
crossing-over
the exchanging of parts in homologous chromosomes in meiosis
recombination
when gene variants originally on the maternal chromosome are now on the paternal chromosome (or vice versa)
haplotypes
- group of genes or dna variations that are inherited together from one parent
haplogroups
- group of related haplotypes
translocations
- rare instances
- nonhomologous chromosomes exchanging segments during meiosis
- may cause infertility, down syndrome, and cancers
monosomy
loss of a chromosome in a pair
trisomy
a gain in number of chromosomes
genotype
a combination of alleles
phenotype
the physical appearance outcome of a genotype
why is the one gene, one Protein model not completely correct
because many traits are polygenic (affected by genes at many more loci than just one or two)
examples of polygenic traits
- height
- skin colour
pleiotropy
when a single gene influences multiple traits or characteristics in an organism
examples of pleiotropy
- sickle-cell
polymerase chain reaction (PCR)
a method of amplifying a tiny sequence of DNA by incrementally increasing the sizes of a billion copies made from it
when is polymerase chain reaction (PCR) used?
- for studying ancient dna
- identification of sex chromosomes documentation of diseases, isolation of unique repetitions of DNA segments
what did we learn from sequencing the human genome?
- that dna segments are often repeated (called microsatellites), sometimes many times for no reason
- microsatellites which form our DNA signature
