Summary
Psy 2413 Chapter 2 - Invitation to the Life Span Summary.
This is a comprehensive and detailed summary on Chapter 2; from conception to birth from the book intro to life span for Psy 2514. *Essential!!
[Show more]
Connected book
Book Title:
Author(s):
- Edition:
- ISBN:
- Edition:
Content preview
Chapter 2From Conception to Birth
Genes and Chromosomes
● Conception begins as a zygote, single cell formed from the union of two
gametes: sperm and ovum
○ Homozygous: referring to two genes of one pair that are exactly the same
in every letter in their code. Most gene pairs are homozygous
● DNA (deoxyribonucleic acid): the chemical composition of the molecules that
contain the genes, which are the chemical instructions for cells to
manufacture various proteins
● Chromosome: one of the 46 molecules of DNA that virtually every cell of the
human body contains and that contain all of the genes. Other creatures has
fewer or more chromosomes
○ Humans have 21,000 genes
○ 46 chromosomes, which are arranged in 23 pairs
◆ not in a gamete (otherwise called a reproductive chromosome)
Variations among people
● Allele: a variation that makes a gene different in some way form other genes
for the same characteristics. Many genes never vary; others have several
possible alleles
○ Heterozygous: referring to two genes of one pair that differ in some way.
Typically one allele has only a few base pairs that differ from the other
member of the pair
Triplets: set of three three pairs where each specifies production of one of 20
possible amino acids
Genetic expression can be important whether or not a gene is expressed, which
means that it becomes active in forming the person
– No single genes for homosexuality, just combinations of it
Myelination alters genes and continues throughout life
● Microbiome: all of the microbes with all of their genes in a community
● Copy number variations: the various repeats of deletions of base pairs that
genes have
○ Everyone has them, correlates with every disease and conditions
Genotype and Phenotype
● Genotype: a collection of genes within a person
● Phenotype: person's actual appearance and behavior; observable
characteristics of a person
, Shared and Divergent Genes
● Genome: an entire set of genes to make a member of a certain species
○ Every race share 99.5% of their genetic codes
○ Humans and chimpanzee are 98% same
Male and Female
● XX female
● XY male
○ 120 males for every 100 females (120:100) probably b/c smaller Y sperm
can swim faster than heavier X sperm and thus reach he ovum first
Y chromosome has fewer genes than X, but has one crucial gene: SRY which
directs the developing fetus to make male rogans
● Autosomes are inherited by males or females (22 of 23)
Twins
● zygote splits completely producing genetically identical cells
● Monozygotic (MZ) twins: twins from one zygote that splits apart very early in
development. Other monozygotic multiple births such a s triplets can occur
○ don't have the same phenotype, develop their own identities (nurture)
● Dizygotic twins (fraternal): twins who are formed when tow separate ova are
fertilized by two separate sperm at roughly the same time. Only have half their
genes in common
Genetic Interactions
● Additive genes: the effects add up and make the phenotype (height, hair, skin
color); genes that each contribute to the characteristics
● Dominant-recessive pattern: when alleles interact and the dominant gene is
more influential than the recessive gene (nonaddictive)
○ if you inherit the recessive gene not present in the phenotype you are a
carrier of that gene
● Carrier: a person whose genotype includes a gene that is not expressed in the
phenotype. The carried gene occurs in half the carrier’s gametes and thus is
passed on to half of the carrier’s children
○ If inherited from both parents, the characteristic appears on phenotype
● X-linked: a gene carried on the X chromosome. If male inherits an X-linked
recessive trait, he expresses that trait b/c the Y from his father has no
counteracting gene
○ Can be cause of colorblindness
○ 20x more boys than girls
The final complexity mentioned here is epigenetic. Genes are affected form the
moment of conception by other materials.
– All important human characteristics are epigenetic including diseases and
disabilities
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller anyiamgeorge19. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $11.99. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
53022 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now