Chapter 2 - Biological Bases and Evolution Flashcards
Genes
- 46 chromosomes
- egg and sperm 23 chromosomes
- consists of DNA
- gene - smallest unit of DNA
- 99% of genes are the same
- proteins - building blocks of cells that direct the body’s processes
Chromosomes and sex
XY - male
XX - male
- 46 chromosomes in 23 pairs, meiosis caues egg and sperm to unpair which join during fertilization
Description of Gene Expression
Genotype - sum of all genes a person inherits
Alle - different versions of a gene
Phenotype - expression of genes that are visable
- Dominant or recessive
Sex-linked genes
Mutated gene on the X chromosome – X-linked inheritance (women are more protected since they have 2 but men only have one)
Sickle Cell Disease
Associated with a single cell is sickle cell disease
- The red blood cells change shape to a sickle shape which may get stuck in the blood vessels
- Makes your immune systems suffer
- RECESSIVE - must be from both parents
Could be heterozygous
- most people asymptomatic
- may have mild disease like deprived O2
Down Syndrome
- distinct facial features
- mental and motor delays
- extra 21 chromosome
- both parents need to have change
- can check in the fetus
- very rare
Evolutionary Theory
Evolution - process of change in gene frequencies over generations
Darwin natural selection - environmental conditions allow some members of the species to survive and pass on their genes to future generations and some do not
Adaptation - promotes orgamism survival in habitat (fit - ability to bear offspring that can live long enough)
- OVER GENERATIONS NOT INDIVIDUAL DIFFERENCES
Polygenic Inheritance
- leads to normal distribution
- when you combine many genes you get a normal distribution rarely people on opposite sides of spectrums (double dominant or recessive)
Evolutionary theory of development
Some traits may be more adaptive at state of development
- Infants poor visual acuity
- increase clinglines in toddlers
- risk taking in adolencen
