CELLS the basic unit of life living things are composed of at least one cell cells metabolize (obtain energy, use energy, make waste) cells can reproduce cells sense and respond to the environment red blood cell brain cell sperm egg Some human cells
Cells need large surface area to volume ratio
Cheek epithelial cells 3 parts of eukaryotic cell
1. plasma (cell) membrane Selectively permeable Lipid bilayer hydrophilic outer/inner portions hydrophobic within
The membrane determines what can get into and out of the cell such as..
Fluid mosaic model Dynamic!
3 types of membrane proteins 1. Receptors bind substances Example: insulin receptor 2. Enzymes Catalyze (speed up) reactions Example: lactase 3. Transporters, Channels ferry substances Example: chloride ion channel
Cystic fibrosis (CF) most common serious genetic disease in the US A single gene mutation causes a cell membrane Cl- transport protein to malfuncton
Cells produce thick, sticky mucus that clogs the lungs infections
2. DNA
Eukaryotic cells have a nucleus that contains DNA Why is DNA important? DNA in nucleus
DNA = instructions for cells to manufacture proteins DNA = genetic material
DNA is in the form of chromosomes 46 long strands of DNA per cell (23 in egg and sperm)
3. cytoplasm (fluid-like interior) Contains ORGANELLES
2 Organelles found in cytoplasm of 1. lysosomes eukaryotic cell Bags of enzymes that clean old parts, digest foreign matter
Tay Sach s disease Mutation in a single gene results in a malfunctioning lysosomal enzyme Lysosomes fill up with lipid (fatty substance) Normal until ~ 1year, brain deteriorates, fatal ~age 3 Microscopic view of affected brain Cherry spot on eyeball
Lysosomes and apoptosis Apoptosis = programmed cell death Ex. Tadpole tail, fingers during human embryonic development Tarahumara Frog (Rana tarahumarae)
Syndactyly 1/2000 births Disappears at 4 months gestation Between 50 billion and 70 billion cells die each day due to apoptosis in the average human adult. In a year, this amounts to the proliferation and subsequent destruction of a mass of cells equal to an individual's body weight.
2. mitochondria produce energy (ATP) use oxygen and fuel (sugar)
Chapter 10 The human life cycle DNA has the instructions
These instructions are on chromosomes which contain units of information called genes
Gregor Mendel (~1850) the father of genetics Worked out the transmission of traits from parent to offspring using pea plants What makes peas good genetic subjects (compared to humans)?
Pisum sativum Single gene traits
Distinct pea plant traits
Start with true-breeding varieties Cross or self pollination Keep detailed records Statistical analysis
1. Particulate theory of inheritance Modern version: Genes are physical units passed from parent to offspring
The monohybrid (one gene) cross
2. Principle of dominance : For each gene we have 2 alleles Dominant allele observed in phenotype (appearance) B = brown eye allele G = yellow pea allele
recessive allele is masked by a dominant allele b = blue eye allele g = green pea allele BUT, each individual has two alleles per gene. What are the 3 possible GENOTYPES?
3. Principle of segregation Modern version: each sperm and egg randomly gets one allele per trait and fertilization gives the new individual 2 alleles per trait
Sickle cell disease S = normal allele s = sickle cell allele Mutation in the gene for hemoglobin Red blood cells form a sickle shape when oxygen is low
The sickled red blood cells cannot fit through capillaries Causes joint pain, anemia why? Over time stresses kidneys, heart, other organs An example of pleiotropy = single gene, multiple effects
Other one gene traits Just because it s dominant doesn t mean most people have it P- S- D- W- A - C-
Albinism (aa)
All people have harmful recessive genes BUT the likelihood that you will mate with another person who has the same allele is low Infantile Neuroaxonal Dystrophy (NAD
Review of other genetic traits Marfan s disease and pleiotropy fig. 10.13
Continuous variation results from many genes (polygenic) Examples:
Bell shaped curve shows continuous variation
IQ is polygenic
phenotype also affected by environment -Skin color melanin production increased by sun -Height is ~90% genetic
Chapter 13
Chromosomes = strands of DNA in nucleus Gene = unit of information on a chromosome DNA = molecule that composes chromosomes/genes
Genes (and alleles) are located on chromosomes Humans have? #chromosomes in each somatic cell nucleus Somatic cell = body cell (not sperm or egg) A human chromosome in nucleus
Chromosomes are copied before a cell divides into 2 cells so that each new cell has a full set
chromosome Note the coiled, thread-like structure
Humans have 2 sets of chromosomes in each cell 23 from egg 23 from sperm n
Homologous chromosomes Chromosomes of (most) animals are in pairs Homologues have same genes at same positions Each chromosome has 100s or 1000s of genes
alleles at gene position may be different Your combination of alleles is unique to you!
Chromosomes and genetics Human 46 Chimpanzee 48 Dog 78 Cat 72 Alligator 32 Goldfish 94 Mosquito 6 Potato 48 Baker s yeast 34 The more complex the organism the more chromosomes??
Karyotype photo of chromosomes arranged according to? Pairs 1 through 22 = autosomes Sex chromosomes are X and Y Note the homologous pairs Cant see individual genes!
Fig. 10.14 Autosomes are the same in male and female The Y chromosome determines sex! What genes are on the Y? The X?
Chromosomal number disorders 47, XX, 21+ Down syndrome Page 136 (ch 9)
Klinefelter syndrome Chromosomal notation?
Chromosomal changes Translocation = piece of one chromosome another
*C. Deletion small piece of a chromosome lost Example: Cri du Chat (pg. 198) High-pitched cry (identified as a cat-like cry) Low weight Poor muscle tone (hypotonia) Microcephaly (small head size) Micrognathis (small jaw) Hypertelorism (wide spaced eyes) Round face Low set ears Feeding difficulties Delays in walking Scoliosis Language difficulties Mental retardation Organ defects 1/50,000 live births
D. Inversion a piece of a chromosome inverts (flips) 16 year old with leukemia (AML) Note this karyotype is from the cancerous cells only Cartoon of cytogenetics UWISC
Genetic testing 1. Of children and adults Obtain chromosomes/dna from cells for testing
2. Prenatal testing 1. ultrasound for fetal anatomy, age, size, twins Can pick up defects such as spina bifida
2. Fetal testing Test fetus in utero
A. amniocentesis Obtain fluid from sac via needle through uterus - contains fetal cells Slight risk of miscarriage, perform ~ week 14 Karyotype or gene test
B. Chorionic villus sampling Tube through vagina into uterus Obtain cells from placenta Greater risk of miscarriage Done at ~week 5
3. Embryo testing In vitro fertilization (IVF) - > Remove one cell from an early embryo > why? Implant embryo in uterus
Ethical implications of embryo testing Could choose gender of child is this right? Could people test for other traits too? Will this lead to eugenics? Health insurance doesn t pay for IVF (usually) or embryo testing who can afford it? How is are the testing centers regulated? Prenatal testing may (does) lead to abortions (even if disorder is not fatal as in Down syndrome) Improves odds of having a healthy baby Could be ready to treat a baby or be emotionally prepared
Genetic profiling What type of genes would you like to know about? Predisposition genes Predict health risk for: Diabetes, cancer, Alzheimer, etc Metabolic profile How a person handles a drug
Ethical implications of genetic profiling Voluntary or required? Insurance companies or employers have your data Could scavenger hunt for predisposition genes Alcoholism, cancer, alzheimer s Who can afford the tests? Counseling needed Is it a good thing to know the future? May influence whether or not to have children