Chapter 3 Genetics

Deoxyribonucleic Acid (DNA)

the chemical composition of the molecules that contain the genes

genes

the chemical instructions for cells to manufacture various proteins

chromosome

molecules of DNA that each cell of the human body contains and that contain all the genes

23

There are 46 molecules of DNA in ___ pairs of chromosomes.

zygote

a single cell formed from the union of two gametes, a sperm and an ovum

allele

a variation that makes a gene different in some way from other genes for the same characteristics

dominant

more influential for whatever trait the gene pair affects (Ex. brown eyes)

recessive

may be hidden in the genotype, and not expressed in the phenotype (ex. Blue eyes, red hair)

carrier

a person carries a recessive gene, and it is not expressed in the phenotype

genome

the full set of genes that are the instructions to make an individual member of a certain species

• the entire packet of instructions to make a living organism

copy number variations

genes with various repeats or deletions of base pairs

• Can affect the likelihood of many inherited diseases like cancers and mental illnesses

gamete

a reproductive cell, sperm or ovum in humans

microbiome

all the microbes that live inside each human body

• Includes bacteria, viruses, fungi, archaea, yeasts

microbe

• have their own DNA and genes

• make up the microbiome

genotype

an organism’s entire genetic inheritance

(ex. you have the gene for blue eyes)

phenotype

development of one’s appearance, behavior, and other brain and body functions

(ex. your eyes are blue)

genotype, environment

phenotype = ________ +_________

homozygous

two genes that are exactly the same in every letter of their code

(ex. you got the blue eye gene from both parents)

heterozygous

two genes of one pair that differ in some way

(ex. you got the brown eye gene from one parents and the blue eye gene from the other)

autosomes

the 44 chromosomes/22 pairs that are independent of the sex chromosomes

23rd pair

the chromosome pair that determines sex

XY

male sex chromosome

XX

female sex chromosome

trisomies

instead of 2 chromosomes at a site, there are three.

Down Syndrome

trisomy of the 21st pair of chromosomes

epigenetics

study of how nature and nurture work together

epigenetics (how nurture and nature work together)

What is this an example of?

Two people may have the same gene linked to stress, but if one grew up in a calm home and the other in a stressful one, they may express that gene very differently. That’s epigenetics in action.

methylation

a process whereby molecules of ribonucleic acid (RNA) and DNA alter the instructions of the genes

• continues from conception to death

RNA

What, besides DNA, has a role in whether genes are turned on or off?

father = Prader-Willi Syndrome (obese, low energy, stubborn)

mother = Angelman syndrome (skinny, high energy, optimistic)

If father passes on a harmful allele on Chromosome 15, what will happen?

if the mother passes it on?

It begins duplicating, and after it duplicates into eight, it starts differentiation where the cells specialize.

What happens to the zygote hours after conception?

differentiation

Cells specialize, taking different forms and reproducing at different rates depending on where they are located

• ex. Some cells become part of an eye, other part of a finger, or part of the brain

Zygote (one cell), morula, blastocyst, embryo, fetus, baby

What are the developmental stages for the zygote?

stem cells

the cells that result from the early duplication and division of the zygote

In Vitro Fertilization (IVF)

mixing sperm with ova that have been surgically removed from a woman’s ovary

• If a zygote is produced, it is inserted into the woman’s uterus, where it may implant and develop into a baby.

surrogate mom

fertilized egg is implanted into another woman, she has the baby, and gives it to the couple whose egg it belonged to

monozyogtic twins

one blastocyst is separated into two before implantation in the uterus; always identical and same sex

dizygotic twins

Two ova are fertilized by two sperm at about the same time; not identical and can be same sex or two different sexes; about half of their genes are in common

sex

one’s assigned sex at birth (biological)

gender

refers to social and cultural constructs

1.2:1

What is the ratio of male to female zygotes?

• to avoid certain genetically linked medical conditions

• preference

Why is prenatal sex selection used?

gestation period

how long the fetus is in the mother’s womb (38 weeks/9 months for humans)

• different for every species

Genetic Predisposition

You have a ______ _________ to develop some things (like alcoholism) if your parents and grandparents have it.

• However, the environment contributes to things like alcoholism.