bio principles test 3

Prokaryotic genome

A single DNA macromolecule, a closed circle

Genome

The total genetic information of a cell or organism

Eukaryotic genome

Several DNA macromolecules, humans have 23 different chromosomes

Most of our cells are _____ and some cells/organisms are _____

Diploid and haploid

Diploid

A cell, nucleus, or organism containing two sets of chromosomes (2n)

Haploid

A cell, nucleus, or organism containing one set of chromosomes (n)

DNA double helix is wound around _____ proteins to for many _____, which are collectively called ______

Histone, nucleosomes, chromatin

Chromosomes are

Linear

What is prokaryotic cell division called?

Binary fission

Step 1 of binary fission

DNA replication

Step 2 of binary fission

Cell elongation, FtsZ protein moves to center of cell

Step 3 of binary fission

Chromosomes moved to opposite sides of cells, FtsZ forms a ring

Step 4 of binary fission

FtsZ directs formation of septum (dividing cell wall) in cell center

Step 5 of binary fission

Cell pinches in two, forming two identical daughter cells

Gap Phase 1

Growth, accumulation of resources, longest stage

Synthesis (building something)

DNA replication, in animals replication of centrosome (contains centrioles, contain microtubules)

Gap Phase 2

Replication of some organelles, further growth and accumulation of resources

Mitosis

Several steps, PPMAT

Prophase

Nucleus, golgi, and ER break down, chromosomes condense become visible distinct, spindle apparatus forms

Prometaphase

Microtubules (part of spindle apparatus) attach to sister chromatids at points called kinetochores

Sister chromatids

Two connected identical copies of a chromosome

Metaphase

Sister chromatids align at center of cell, positioned to move to opposite sides of the cell

Anaphase

Sister chromatids split, spindle apparatus pulls the, to opposite sides of cell

Telophase

Chromosomes de-condense, nucleus, golgi, and ER reform x2

Cytokinesis

Cleavage furrow (animal) or cell plate (plant) separates cell in two identical daughter cells

G0 (resting phase)

Not part of cell cycle, offshoot- after cytokinesis, before G1, cells in G0 are not actively dividing they are fulfilling their normal functions

Where are most cells?

In G0

G1 checkpoint

Checks for energy and resources for DNA replication and damage to DNA

G2 checkpoint

Checks for damage to DNA

M (metaphase) checkpoint

Checks that all sister chromatids are connected to spindle apparatus

Cells need …

Permission from surrounding cells to divide, this maintains normal cell number/density

There are many ____ involved in regulating cell cycle

Proteins

Cancer

Uncontrolled cell growth, which causes harm, caused by faulty cell cycle control proteins, caused by mutations in the DNA sequence, caused by un-repaired DNA damage

Proto-oncogene

A normal gene involved in the cell cycle that, when mutated, becomes an oncogene

Example of tumor suppressor gene/protein

p53

p53

Locates damage to DNA and brings in DNA repair proteins, if repair is successful, cell cycle proceeds, if damage is too severe, causes apoptosis

Apoptosis

Programmed cell death

If p5 is mutated

No longer encodes a functional protein, allows cell with damaged DNA to divide, leads to more mutations, more oncogenes

Virtual all eukaryotic cells are

Capable of sexual reproduction

Sexual reproduction results in

More diverse offspring than asexual reproduction

High diversity among offspring

Increases likelihood of survival

Meiosis is done by

Special germ cells

Meiosis I

PPMAT I

Prophase I

Nucleus, golgi, and ER break down, chromosomes condense, synapsis, allows for crossover

Synapsis

Formation of tetrads

Oncogene

A mutated version of a normal gene involved in the cell cycle- can lead to cancer

Tetrad

Two duplicated homologous chromosomes (four chromatids) bound together during prophase I

Homologous chromosomes have

The same genes, but the exact sequences are different

Prometaphase I

Microtubules attach to tetrads

Crossover

The exchange of genetic material between homologous (non-sister) chromatids, resulting in chromosomes that incorporate genes from both parents of the organism

Metaphase I

Tetrads align at center of cell, their orientation is random- different daughter cells will receive different homologous

Anaphase I

Tetrads pulled apart, sister chromatids go to same side

Telophase I

Chromosomes de-condense, nucleus, Golgi, and ER reform x2

Cytokinesis (after telophase)

Result 2 “haploid with replicated DNA” cells

Where is there no interphase?

Between meiosis I and meiosis II

Meiosis II

PPMAT II, just like mitosis

Cytokinesis (after meiosis II)

Result: four haploid cells

Chromosomes contain

genes

Genotype

the underlying genetic makeup of an organism (can’t see)

Phenotype

the observable traits expressed by an organism (you can see)

What do most genes encode?

proteins

Genotype leads to

phenotype

A given gene can have different versions/variations called

alleles

Diploid organisms have two copies of each chromosome, which means

two copies of each gene

Homozygous

two of the same allele

What phenotype will homozygous have?

the allele version they have

Heterozygous

two different alleles

For any given gene

one allele is dominant and the other is recessive

What phenotype will heterozygous have?

the dominant allele

What are the 3 possible genotypes?

homozygous dominant, homozygous recessive, and heterozygous

Parents are both diploid but

only pass on one of each chromosome to offspring

How is the version of each chromosome put into egg/sperm chosen?

randomly

Punnett square

used to predict possible genetic outcomes of offspring, usually one gene at a time

What does each box of the Punnett square represent?

25% probability of possible offspring

What do many human traits/diseases follow?

Mendelian Inheritance patterns

Polygenic inheritance

phenotype is the result of two or more genes

What does polygenic inheritance lead to?

continuous variation

Continuous variation

an inheritance pattern in which a trait/phenotype shows a range of values

Incomplete dominance

heterozygotes are intermediate in appearance between the two homozygous

Codominance

the complete and simultaneous expression of both alleles in a heterozygote

Example of multiple alleles

ABO blood types in humans

Recessive lethal

an allele that’s only lethal when homozygous

Recessive lethal in heterozygote

may or may not have an effect on phenotype

What system do most mammals use for biological sex determination?

X/Y

X and Y chromosomes are

two versions of the sex chromosome

All other chromosomes are called

autosomes

Autosomes are

not directly involved in sexual development

X chromosomes

have many genes required for life, directs development to female sex

Y chromosome

no genes required for life, alters x-directed development, leading to male sex

We are diploid so we have

two copies of the sex chromosome

How can sex be determined in other animals?

through different mechanisms

X-linked traits

gene located on X chromosome

XY individuals are most likely to have a trait because

they have only one copy of the gene

Epistasis

an antagonistic interaction between genes such that one gene masks or interferes with the expression of another

Example of epistasis

coat color of mice

What is DNA made of?

nucleotides

5’ phosphate of one nucleotide is connected to what?

3’ OH of the next

Two strands of DNA form

a double helix

What is a double helix held together by?

H bonds between bases

Two strands of DNA in the double helix run

antiparallel to one another