exam1

ecology

the study of how organisms interact with each other and their environment

evolution

underlying process that accounts for the diversity of life on Earth

evolution explains:

unity and diversity

adaptation

an inherited characteristic of an organism that enhances its survival and reproduction in a specific environment

evolution starts with:

same species variation

Darwin’s two major points

descent with modification & natural selection

descent with modification

changes from common ancestors

natural selection

the mechanism behind descent with modification

taxonomy

the branch of biology that names and classifies species into groups of increasing breadth

domains are

the broadest units of classification

number of domains

3

list all domains

archaea, bacteria, and eukarya

list all classification groups

domain, kingdom, phylum, class, order, family, genus, species

scientific name

species + genus

prokaryotes’ domain(s)

archaea & bacteria

chromosomes

discrete units of DNA, within the nucleus of eukaryotic cells

chromatin

the entire complex of DNA and proteins that is the building material of chromosomes

DNA is made up of

deoxyribose, nitrogenous base, and phosphate

DNA helix is held together by

hydrogen bonds

complementary bonding

A only binds to T, G only binds to C

Rosalind Franklin discovered

the double helix structure of DNA

genetic code

the four nitrogenous bases that comprise DNA

DNA’s structure

allows for copying of genetic info

DNA’s sequence

carries info for function

8 types of proteins

enzymatic, defensive, storage, transport, hormonal, receptor, contractile/motor, and structural

protein’s structure

enables its diverse functions

triplet

every 3 DNA bases, that each code for one specific amino acid

advantages of forming gametes

reshuffles genes, doesn’t increase the amount of chromosomes every reproduce

gametic cells

one copy of each chromosome, or half of the full genetic information

meiosis

produces gametes

Why did Gregor Mendel use peas for his experiments?

Many distinct traits, mating could be controlled, able to do both cross fertilization and self fertilization, short generation time

character

heritable feature that varies among individuals

trait

each variant for a character

true breeding

have consistently produced the same phenotype

blending

the general idea before Mendel, the theory that genetic material contributed by parents mixes together

particulate

parents pass on discrete heritable units (genes) that retain their separate identities in offspring

Law of Segregation

2 alleles for a heritable character segregate during gamete formation and end up in separate gametes

monohybrid cross

crossing a homozygous dominant with a homozygous recessive

complete dominance

dominant allele masks recessive allele completely, Mendel’s observation

codominance’s major example

blood types

incomplete dominance

blending

epistasis

the phenotypic expression of a gene that alters that of a gene in a second locus

frequency of dominant alleles

dominant alleles are not necessarily more common in populations

pleiotropy

genes that have multiple phenotypic effects, ex. sickle-cell or cystic fibrosis

epistasis is an example of….

pleiotropy

polygenic inheritance

an additive effect of two or more genes on a single phenotype, ex. height or skin pigmentation

quantitative characters

those that vary in the population along a continuum, usually indicate polygenic inheritance

carriers

heterozygous individuals who carry the recessive allele but are phenotypically normal

consanguineous mating

between two close relatives, increase the chance that both parents can carry the same rare allele

cystic fibrosis

the allele results in a buildup of chloride ions outside the cell and can cause death by the age of 5 if not for modern medicine

Huntington’s disease

a dominant allele disease, but it reveals itself only after 40 years, so you might have already reproduced and passed it to your offspring

sickle cell disease

heterozygotes exhibit some sickle-cell symptoms, but also this advantages heterozygotes to be able to fight malaria, an instance where there is an advantage for carriers (ex. of heterozygote advantage)

heterozygote advantage

an allele might be very disastrous when expressed, but is passed on due to how it supports heterozygotes

amniocentesis

the liquid that bathes the fetus is removed and tested for certain genetic disorders

chorionic villus sampling (CVS)

a sample of the placenta is removed and tested

homologous chromosomes

for 1 type of chromosome there is a second gene in the corresponding location

Morgan’s experiments ….

on fruit flies, provided evidence that genes are physically located on chromosomes

Why did Morgan use fruit flies?

Easy to raise, short generation time, abundant offspring, only 4 pairs of chromosomes

2 types of sex chromosomes

a larger X chromosome and a smaller Y chromosome

human female sex chromosomes

XX

human male sex chromosomes

XY

sex-linked gene

a gene that is located on either sex chromosome

number of genes on the human Y chromosome

only 78, so not a lot of Y linked mutations

number of genes on human X chromosome

~1100 genes

sex chromosomes have …

genes for characters both related and unrelated to gender

X-inactivation

evolved to equilibrate the amount of alleles on X (because men don’t have 2 X chromosomes), one X is suppressed randomly, done to keep the advantage of heterozygosity, happens during development, reversible during gamete formation

Barr body

the chromosome randomly selected during development to be deactivated, densely compacted, attached to nuclear membrane

trisomy in humans

males or females with an extra X chromosome

trisomy 23

Down syndrome

embryos missing a chromosome

are usually not compatible with life

trisomy with sex chromosomes

can lead to fertility issues

trisomy can occur during

1) nondisjunction of homologous chromosomes in the first part of meiosis, 2) nondisjunction of sister chromatids in the second part of meiosis

crossing over causes

recombinant genes

linkage map

mapping of where genes are on a chromosome based on the recombinant rate

centimorgan

unit of measurement for recombinant frequency

at >50% chance of crossing over

you can’t say certainly 2 genes are on the same chromosome

nondisjunction

pairs of homologous chromosomes don’t separate normally during meiosis, and one gamete receives two of the same type of chromosome while the other gamete receives no copy

aneuploidy

the fertilization of gametes in which nondisjunction occurred

monosomic zygote

has only 1 copy of a particular chromosome, usually not compatible with life

trisomic zygote

has 3 copies of a particular chromosome

polyploidy

a condition in which an organism has more than 2 complete sets of chromosomes, more common in plants not animals

triploidy (3n)

3 sets of chromosomes

Turner syndrome

monosomy X, women missing an X chromosome who are sterile, but able to survive

types of mutations

deletion, duplication, translocation, inversion

deletion

removes a chromosomal segment

duplication

repeats a chromosomal segment

inversion

reverses a segment’s sequence within a chromosome

translocation

moves a segment from one chromosome to a non homologous chromosome

genomic imprinting

an epigenetic modification where phenotype doesn’t always directly relate to genotype, affecting any autosomal chromosomes, and depends on if the allele is inherited from mother or father, reversible when gametes are produced

difference between X-inactivation and genomic imprinting

X-inactivation is in sex-linked chromosomes, genomic imprinting is in autosomal

homeostasis

the maintenance of internal stability despite differing environmental conditions (ex. sweating)

8 characteristics of living organisms

cellular composition, order, energy processing, evolutionary adaptation, growth and development, homeostasis, reproduction, response to stimuli

organism

individual living things

organs

collection of tissues and has specific functions in the body

cell

fundamental unit of structure and function, smallest unit of life

community

the array of organisms inhabiting a particular ecosystem

tissue

groups of cells that work together to perform a specialized function

molecules

chemical structure made up of two or more units of things called atoms

ecosystem

all living things in a particular area and non living things with which life interacts

biosphere

consists of all life on earth and the places life exists