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UD - HDFS 220 - Week 4 Notes - Class Notes

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UD - HDFS 220 - Week 4 Notes - Class Notes

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background image Lecture Notes  Saturday, September 16, 2017
10:37 AM
Chapter 3:Nature Through Nurture: Genes and
Molecular genetics, Behavioral genetics, and Behavioral genomics  Molecular genetics: research focused on the identification of particular  genes and how they work o At cellular level -- what are genes and what are they doing ?   Behavioral genetics: research to determine the degree of genetic basis for  a behavior, trait, or ability o How much of differences are due to genes vs. environment  o Measure of heritability  Heritability - a measure of the extent to which genes  determine a particular behavior or characteristics (range from 0-1)  Behavioral genomics: a line of research that combines the above by trying  to identify specific genes that are linked to specific behaviors o Newest type of research o Combines molecular and behavioral   
Our Genetic Beginnings 
When a father’s sperm penetrates a mother’s egg during fertilization, the  result is a zygote. The sperm and egg cells each contain half of our genetic material: 23  chromosomes are donated by the egg, 23 by the sperm, forming 23 pairs. o The first 22 pairs are identical o The 23rd pair  XX = Female  XY = Male  o Only the father may donate an X or Y chromosome, meaning his genes  determines sex of the child  Boys are more at risk for disorders and diseases (most disorders  are recessive -- girls have full set of X's the other X is kind of a back 
up, boys only have one X) 
Each chromosome is made up of DNA molecules
background image DNA: made up of sugar, phosphate, and 4 nitrogen bases that join to form  base pairs: o Guanine (G) pairs with Cytosine (C) o Adenine (A) pairs with Thymine (T) DNA has double helix structure  Once these bases pair they form this double helix shape   
What is a Gene? 
At certain points along the chromosomes, the base pairs are organized into  units called genes Gene:  A segment of DNA on a chromosome that is responsible for telling the body to create proteins that are the basis for the body’s development and 
o The biological unit of heritability  
What do Genes do? 
Basically, serve as a set of instructions, telling the body what to do o Active genes provide codes telling the body to produce specific  proteins These proteins may become body parts, hormones,  neurotransmitters, etc. They may also direct cell activity and help 
cells communicate with one another
“Silent” genes were once thought to be junk… we now know that they also  perform important functions, such as regulating the function of active genes o Example: genes associated with puberty  Turning on other genes and telling them to produce hormones?  The sequence of base pairs within genes provides genetic instructions These base pairs make up the genes like words make up sentences. o Decoding  “ATCATCTTTGGTGTT”… o Is like breaking up “Gotothegrocerystorepickupmilkcomehome”  “Got oth. egro ceryst orepick upm ilk. comeho me”, or… “Go to the grocery store. Pick up milk. Come home.”  
We've Mapped all the Genes in Humans  Genome: all of our genetic information together
background image Human Genome Project: finished mapping the entire human genome in  2003 o Found we have 20,000 - 25,000 genes  o Still know relatively little about what specific genes do   
Gene Variation 
Humans share 98-99% of their DNA with chimpanzees. About 99.5% of human DNA is identical in all people.  The remaining 0.5% can vary between individuals, and is part of what  accounts for variations in traits and characteristics. Mutations, or changes in the structure of a gene, can also occur (either during conception or over the life course), resulting in further variation between 
o Everyone has mutations  o Most are harmless or adaptive  o Same contribute to diseases or disorders, like cystic fibrosis, autism,  schizophrenia   
Genetic Mutations 
Can involve changes in single nucleotides, larger changes in the number of  nucleotides, deletion of nucleotides, or insertions of additional nucleotides 
“pick up milk” ) o Single nucleotide change becomes “pack up milk” o Change in the number of nucleotides becomes “pick upupupupupup milk” o Deletion of nucleotides becomes “pick milk” o Insertion of nucleotides becomes “pick up no milk” Some of these changes really do make a difference (coding for different  proteins, meaning different instructions) , but sometimes it does NOT matter 
and does NOT make a difference 
  Mendelian Inheritance 
background image Genotype - actual genetic information that determines our species and  influences unique characteristics Phenotype -  directly observable characteristics (example: eye color);  expression of one's genotype and environmental influences  Not every change / mutations in genotype results in changes in phenotype   
Mendelian Inheritance: Dominant and Recessive Genes 
While we inherit genes from both parents (one set of 23 chromosomes each),  we don’t display everything they give us Some genes are dominant  o And will always display in our phenotype Some genes are recessive  o Will only display in our phenotype with 2 copies of the same  chromosome for that trait   
Genes and Eye Color 
So, genes play a role in physical development, including disease 
Some diseases/disorders involve single genetic mutations (usually recessive)  that are either inherited or spontaneous o Most genes carrying disease are recessive- we have a back-up!

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School: University of Delaware
Department: Human Development
Professor: Jennifer Carrano
Term: Fall 2017
Name: Week 4 Notes
Description: Week 4 Notes
Uploaded: 10/21/2017
15 Pages 15 Views 12 Unlocks
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