chapter 2 human dev

DNA

deoxyribonucleic acid, the double helix molecule whose chemical code makes up chromosomes and serves as our genetic endowment; it is made up of sequences of the chemicals A (adenine), C (cytosine), G (guanine), and T (thymine).

gene

small portion of DNA that codes for a protein

where are genes located

located in the nucleus

what does a gene code for

a protein

what are the nucleotide pairs

adenine + thymine

guanine + cystosine

nucleosomes function

organize DNA

help form chromosomes

a gene is made up of many sets of

3 base pair sequences

(which code for a particular amino acid)

4 nucleotides

guanine

cystosine

thymine

adenine

this “triplet code” specifies an

amino acid

chromosomes

histone protein clump (nucleosome) + DNA strand wrapped around it.
- allows control of gene "expression".
- threadlike structure made up of genes; in humans, there are 46 chromosomes in the nucleus of each cell

how many pairs of chromosomes do humans have

23 pairs

how many total chromosomes do humans have

46

where do we get our chromosomes

1 chromosome of each pair from mom/dad

what is a karyotype

a picture of the matched pairs of a chromosome

who detirmines the sex of the baby

the father,

the mom can only give an x but the father can give an x or y

according to human genome project, humans have how many genes

20,000

whats special about chromosome #23

detirmines sex

genotype

the genetic makeup of an individual.

phenotype

physical presentation of genes

allele

a variant form of a gene that can produce different traits.

various ways a gene may express itself/ different phenotypes for genes

dominant

need ½ of alleles to show

dominant is always seen , phenotype

recessive

need 2/2 alleles to show this trait

only seen if u have two copies

incomplete dominance

expresses trait some of the time

no trait is dominant over the other where both alleles contribute to the phenotype, resulting in a mix of characteristics.

ex: sickle cell anemia

red + white = pink

co-dominance

both traits expressed all of the time

ex: AB blood type

red + white = red and white

carrier

does not express trait but can pass it onto offspring

has only one copy of a gene for a recessive trait

ex: blue eyes

poly-genetic

many genes contribute to a single trait, leading to a range of phenotypes.

ex: eyes or skin, different shade ranges

chromosomal abnormalities

trisonomy 21

sex chromosomes

klinefelters syndrome

super male

turners syndrome

triple x

sickle cell anemia

recessive + incomplete dominance

• genetic blood disease in which red blood cells assume an unusual sickle shape and become inefficient at distributing oxygen throughout the body.

• causing breathing problems and pain

sex linked disorders

red/green color blindness

hemophilia

muscular dystrophy - duchennes type

some forms of deafness and night blindness

PKU

phenylketonuria (PKU) - RECESSIVE genetic disease in which a child is unable to metabolize phenylalanine; if left untreated, it soon causes hyperactivity and intellectual disability

hemophilia

- CARRIER + sex-linked inheritance

- deficiency in the blood's ability to clot

- more common among males than females bc it is associated with a sexlinked gene on the X chromosome

huntingtons disease

dominant

40 repeats on CAG

excess glutamine causing mis-folding of the protein.

jerky movements, cognitive decline, psychiatric problems

whos research is responsible for discovering the gene of huntingtons

nancy wexler lead to the discovery of the gene for Huntington's - had to learn how disease traveled between generations, took skin biopsies and blood samples from those they interviewed, found double dose population

what is CNV

-copy number variation
- instances in which a person receives too many or too few copies of a stretch of DNA; like gene mutations, they can either be inherited from a parent or arise spontaneously and can contribute to diseases and disorders

behavioral genetics

• the study of the relationship between genetics and behavior, exploring how genetic factors influence individual differences in behavior and psychological traits.

determination of genetic disorders

the process of identifying genetic conditions through various testing methods, such as genetic testing and family history analysis, to understand the influence of genes on health and disease.

prenatal diagnostic tests

Ultrasound
fetal MRI
chorionic villus sampling (CVS)
amniocentesis
maternal blood sampling (triple screen)
PGD
Sex determination

chromosomal abnormalities

Trisomy 21
Turner’s
Klinefelter’s
Others:
Androgen insensitivity Syndrome
5-alpha reductase deficiency

trisomy 21

extra chromosome on 21

down syndrome

almond eyes, lower iq, characteristic facial features, developmental delays.

turners syndrome

ONE X chromosome

failure to start puberty

short

underdeveloped breasts

sterile

klinefelters syndrome

XXY

male with female characteristics

develop breasts, female body, weight around waist

IQ is normal but may have learning trouble

androgen insensitivity syndrome

the body is unable to respond to male hormones (androgens), such as testosterone. 

5- alpha reductase deficiency

the body lacks the enzyme 5-alpha reductase, which converts testosterone to dihydrotestosterone (DHT)

what is the ‘fingerprint’ on top of certain genes that influences whether or not these genes are turned on or not’

epigenic marks

epigenetics

Epigenetics alter the expression of genes without any change in the actual DNA sequence

what is meant by gene expression

genes must be read in order to carry out their instrunctions

what are the two epigenetic mechanisms

histone acetylation

DNA methylation

which epigenetic mechanism involves the nucleosome

histone acetylation

histone acetylation

Forming the chromosome, DNA strands roll over nucleosomes’, which are a cluster of nine histone proteins. Acetylation of the histone proteins removes positive
charges, thereby reducing the affinity between histones
and DNA.
-Allows RNA polymerase and transcription factors
easier access to the promoter region.
Therefore, in most cases:
histone acetylation enhances transcription,
histone deacetylation represses transcription.

DNA methylation

Addition of a methyl group (CH3) to the DNA's
cytosine base.
-Usually represses transcription.
-The methylation pattern is heritable after cell
division. Therefore, plays an important role in cell
differentiation during development

Turns off
transcription by
causing the
promotor region
to be blocked.

Gotlieb’s Epigenetic Theory.

how genes and their products interact with the environment to guide development and influence phenotypic outcomes.

darwins main arguments

1- gene variation

2- beneficial traits

3- individuals with these genes are more likely to survive and pass it on

4- genes that help with survival will be passed on

5- genetic makeup of species slowly changes

natural selection

if ur genes fit/help u survive for an environment u will survive /reproduce and ur traits will be passed on

rat pup study

A study examining maternal behaviors and their effects on the development and stress responses of offspring.

what was the example of moths and their rural vs industrial environment niches

The Peppered Moth study, which showed how industrial pollution led to dark-colored moths becoming more prevalent in urban areas due to camouflage.

silver fox

A domesticated fox that has been selectively bred for tameness and social behaviors, leading to changes in physical traits and temperament.

evolution is about the interaction of _____ and ______

genes and environment

2 processes of sexual reproduction

meiosis and fertilization

crossing over

chromosomes exchanging material among themselves

mutation

spontaneous change in DNA material (1 or more nucleotide pairs) due to radiation, age, chance, incorporated permanently into future copies of gene

migration and patterns of mating

meiosis

makes sperm/egg gametes through spermatogenesis or oogenesis, 2N (2 copies of each gene/chr) parent cell duplicates DNA and creates 4 daughter cells which each have half# of chromosomes as parent cells 1N (only 1 copy of each gene/chr)

mitosis

no genetic variation, SOMATIC (body) cell reproduction, normal cell division, genetically identical cells, 2N parent cell (2 copies of each gene/chr) DNA duplicates complete set of DNA with same # of chromosomes as parent cell into daughter cell, exact replica

migration and patterns of mating

Migration can influence mating patterns by altering sex ratios in certain locations, potentially changing individual mating strategies and assortative mating (mating with individuals of similar characteristics)

genetic relatedness numbers

parent- 50%

sibling- 50%

grandparent - 25%

MONOZYGOTIC TWINS- 100%

FRAT TWINS- 50%

gene environment correlation/types

Gene-environment correlation refers to the ways in which an individual's genes can influence their environment, and vice versa. The main types include passive, evocative, and active correlations, which describe different interactions between genetic predispositions and environmental factors.

passive

general home env

* env reinforces/correlates w/genotype

- phenomenon in which, because parents provide children with both their genes and a home environment compatible with those genes, the home environments to which children are exposed are correlated with (and typically reinforce) their genotypes. Contrast with active gene-environment correlation and evocative gene-environment correlation.

evoactive

reactions unknowingly generate/evoke response from others
* genotype evokes reactions that (force) make env correlate
- phenomenon in which children's genotypes evoke certain kinds of reactions from other people so that their genetic makeup and experiences are correlated. Contrast with active gene-environment correlation and passive gene-environment correlation.

active

you create/seek out

genotype INFLUENCE env you want

- phenomenon in which children's genotypes influence the kinds of environments they seek out and therefore experience. Contrast with evocative gene-environment correlation and passive gene-environment correlation.

How may the relative importance of the three types of interactions may change with age

as humans develop, they become increasingly able to build their own niches, so active gene-environment correlations become increasingly important - choosing and creating our environments, we actively contribute to our own development

Diathesis stress

explains that mental and physical disorders arise from the interaction of a diathesis (a genetic or biological vulnerability) and stress (environmental or psychological events)

Differential susceptibility.

diff genetic makeups react diff to good/bad env