save me from bio

What are the four most common elements in living matter?

Hydrogen, Oxygen, Nitrogen, and Carbon --make up 96% of all living matter.

Properties of Acids

Donate H+ to a solution, accept electrons, and have a pH of <7

What happens in the S phase of the cell cycle?

DNA Synthesis

What happens in the G1 phase of the cell cycle?

Growth -- cell contents are duplicated.

What happens in the G2 phase of the cell cycle?

More growth and preparation for division.

What happens in the M phase of the cell cycle?

Mitosis (and cytokinesis -- division of the cell).

What are the subphases of mitosis?

Prophase, Pre-metaphase, Metaphase, Anaphase, and Telophase.

How many checkpoints are there in the cell cycle?

3 -- G1 checkpoint, G2 checkpoint, and the M checkpoint.

What is a Karyotype?

A layout of Metaphase chromosomes matched with their homologous pairs.

What is a diploid cell?

A cell with 46 chromosomes -- somatic cells.

What is a haploid cell?

A cell with 23 chromosomes -- sex cells.

What does the mesoderm give rise to?

the notochord (similar to a spinal chord).

What does the endoderm give rise to?

the digestive tract.

What does the ectoderm give rise to?

the nervous system (brain)/neural plate.

If 2n = 18, how many chromosomes come from the mother?

9 -- half from mom and half from dad

Meiosis

Meiosis is a specialized type of cell division that reduces the chromosome number by half, creating four haploid cells, each genetically distinct from the parent cell that gave rise to them.

What two structures does the chiasma connect?

Non-sister chromatids.

What are the steps of meiosis?

Prophase I, Metaphase I, Anaphase I, Telophase I & cytokinesis (then a second set of phases)

What does meiosis 1 deal with?

homologous chromosomes.

What happens in prophase 1?

The chromosomes condense, the nuclear envelope breaks down, chromosomes cross over, and meiotic spindle forms.

What happens in metaphase 1?

the pairs of homologous chromosomes are now tightly condensed and coiled and become arranged on the metaphase plate.

What happens in anaphase 1?

the pairs of chromosomes are pulled apart by the spindle fibers (microtubules).

What happens in Telophase 1 and cytokinesis?

The homologous chromosome pairs complete their migration to the two poles as a result of the action of the spindle. Now a haploid set of chromosomes is at each pole, with each chromosome still having two chromatids. A nuclear envelope reforms around each chromosome set, the spindle disappears, and cytokinesis follows.

What happens during meiosis 2?

sister chromatids separate.

What happens in prophase 2 of meiosis?

A new spindle forms around the chromosomes.

What happens in metaphase 2 of meiosis?

Metaphase 2 chromosomes line up at the equator.

What happens in anaphase 2 of meiosis?

Centromeres divide chromatids move to opposite poles of the cells.

What happens during telophase 2 of meiosis?

A nuclear envelope forms around each set of chromosomes and the cytoplasm divides.

What makes meiosis a unique form of cell division

Synapsis and crossing over -- occurs in prophase 1, pairing up of homologous chromosomes, homologous chromosomes cross over and exchange corresponding genetic information (the DNA exchanged contain the same genes, but may have different alleles).

How does meiosis increase genetic variability?

Independent assortment (meiosis 1 -- homologous chromosomes separate independently), crossing over (genetic recombination, prophase 1), and random fertilization (any egg can join with any sperm -- most effective way to obtain genetic variability).

What is the law of segregation?

Alleles coding for the same trait separate independently during gamete formation.

What is non-disjunction?

When homologous chromosomes or sister chromatids do not separate properly.

What is a character?

An observable heritable feature that may vary among individuals. Ex: flower color.

What is a trait?

One of two or more detectable variants in a genetic character. Ex: purple flower color/white flower color.

What does the blending theory state? Is this true?

The offspring is a blend of both parents (ex: a tall mom giraffe + a short dad giraffe = a medium height giraffe). This is not true because if so, every single offspring would look the same.

What does particulate inheritance state? Is this true?

Different traits are inherited in separate distinct units (genes) (ex: F1 and F2 generations). This is always true because of not every offspring looks the exact same (has the exact same genetics).

What is an allele?

An alternate form of a gene (ex: the gene that determines hair color).

What does the Law of Segregation state?

The Law of Segregation states that two alleles in a pair segregate into different gametes. (this deals with separation of homologous pairs in Meiosis 1 producing haploid daughter cells after Meiosis 1).

What does Independent Assortment state?

Each pair of alleles assort/segregate separately from each other during gamete formation. AKA no gene linkage.

What did Mendelian Genetics assume?

Gregor Mendel, through his work on pea plants, discovered the fundamental laws of inheritance. He deduced that genes come in pairs and are inherited as distinct units, one from each parent. Mendel tracked the segregation of parental genes and their appearance in the offspring as dominant or recessive traits.

What is a dominant allele?

An allele that is fully expressed in the phenotype of the heterozygote.

What is a recessive allele?

An allele whose phenotypic effect is not observed in the heterozygote.

What is a test cross?

A method of determining the genotype of an individual with a dominant phenotype. We cannot know the genotype of an organism if they express the dominant trait because they can be either homozygous dominant or heterozygous. Process: cross the individual with an unknown genotype to a homozygous recessive individual and observe the phenotype of the progeny.

What is incomplete dominance?

When one trait is not completely dominant over the other. Ex: crossing red and white flowers leads to pink flowers when heterozygous instead of the red allele completely dominating over the white allele.

What is co-dominance?

When two alleles affect the phenotype in distinguishable ways. Ex: blood type -- Ia and Ib are both dominant over i. Therefore, Ia and Ib are co-dominant to i.

What is pleiotropy?

When one gene affects more than one phenotype. Ex: sickle cell anemia produces multiple symptoms (symptoms would be equivalent to phenotypes).

What is epistasis?

When a gene at one locus alters the expression of a gene at another locus. Ex: gene 1 determines black or brown coat color and gene 2 determines if pigment is deposited.

What is polygenic inheritance?

When multiple genes affect a phenotype and phenotypes are in a range or spectrum. This range is called a normal distribution. Most likely phenotype = immediate phenotype and the least likely phenotype = the extreme phenotype. Shaped like a bell curve -- immediate in middle with high peak and extreme on both ends.

What can impact the phenotype of an organism?

Environment (ex: hydrangeas -- the acidity of the soil determines their color no matter their alleles), diet, epigenetics, etc.

Is albinism dominant or recessive?

recessive.

Is Achondroplasia (dwarfism) dominant or recessive?

dominant.

Is Huntington's disease dominant or recessive?

dominant.

What did Thomas Hunt Morgan study/discover?

Morgan studied drosophila (fruit flies) and their eye color. He discovered that certain genes such as fly eye color are on specific chromosomes (ex: the X chromosome). This proved that genes are located on specific chromosomes.

What is a wild type?

A normal, unaffected phenotype.

What is a parental phenotype?

Phenotype of parent generation.

What is a non-parental phenotype?

Different phenotype from parents.

What are recombinant offspring?

Offspring that have a non-parental phenotype.

What is a recombinant frequency?

How often do you produce a recombinant offspring.

When are 2 genes considered "linked"?

If they are inherited together (located near each other on the same chromosome).

When will genes assort independently?

If they are far apart on a chromosome -- not linked.

A large % of offspring will have what phenotype?

The parental phenotype.

A small % of offspring will have what type of phenotype and why?

they will have the non-parental phenotype because linkage can break.

What causes gene linkage to break?

The crossing over at chiasmata during prophase 1.

What are the purpose of recombination frequencies?

They are used to map the placement of genes on a single chromosome. This map is called a "linkage map".

What does a larger recombination frequency mean?

The genes are farther apart.

What does a smaller recombination frequency mean?

The genes are close together.

What happens if a disease is displayed on an X chromosome in a male.

The male is forced to express the disease (allele) on the X chromosome no matter if it is dominant or recessive because there are no other X chromosomes to be expressed. Whereas females can be carriers without expressing the disease because the other X can be expressed instead.

How do females account for having more than 1 X chromosome?

The cells randomly convert 1 chromosome into a barr body. Since males have one X chromosome, females will shut off one of their X chromosomes randomly to prevent over expression.

What is a Barr body? How does it happen?

An inactivated X chromosome. Random inactivation occurs by condensing the chromosome (therefore these genes cannot be expressed since no transcription machinery cannot access the genes).

What happens in deletion?

A deletion removes a chromosomal segment.

What happens in duplication?

A duplication repeats a chromosomal segment.

What happens in inversion?

An inversion reverses a segment within a chromosome.

What happens in translocation?

A translocation moves a segment from one chromosome to another, non-homologous one.

When does genomic imprinting happen?

During the formation of gametes.

What happens in genomic imprinting?

It silences one allele of a particular gene from either your mom or your dad.

What are 3 ways genes are regulated to impact transcription?

Chromatin structure, histone modification, and DNA methylation.

Can genes be regulated during translation?

Yes! Genes are regulated all throughout gene expression, and both transcription and translation are involved in gene expression.

What is the structure of chromatin?

DNA + histones (proteins in chromatin that help compact DNA) complex in the nucleus.

What are euchromatin?

Euchromatin are loosely packed and easier to access (increased transcription).

What are heterochromatin?

Heterochromatin are highly packed and hard to express (reduced transcription) ex: telomeres and centromeres.

Why is it hard for heterochromatin to be expressed?

Because the proteins associated with transcription have a hard time accessing the DNA due to the DNA being densely packed.

What is histone acetylation? What is its purpose?

A process that adds acetyl groups to the positively charged lysines on histone tails. The purpose is to loosed the chromatin and allow for transcription to begin.

What is DNA Methylation?

A process that inactivates DNA through the addition of methyl groups. Used in genomic imprinting. This information is then passed down to future generations. This process also reduces transcription.

What do activator proteins do?

Bind to an enhancer and promote transcription.

What do suppressor proteins do?

Block transcription.

How do activator proteins work?

They have two domains (regions). One binds to DNA, the other activates DNA.

What are the 3 steps to activator proteins beginning transcription?

1.) the activator binds to the enhancer.

2.) DNA bending protein binds and transcription factors bind to a promoter.

3.) formation of active transcription initiation complex.

What is the end result of gene regulation at the initiation of transcription?

Depending on which combination of activators are around the enhancer and interacting with it, certain cell types will form (liver cell, lung cell, etc.).

What are 3 ways genes are regulated during translation?

Alternative RNA splicing, mRNA degradation, and blocking of initiation of translation.

What happens in alternative RNA splicing?

The splicing out of keeping different eons.

What happens in mRNA degradation?

Via shortening the poly A tail/removing the 5' cap, the mRNA gets degraded by nuclease.

What happens in the blocking of initiation of translation?

Via regulatory proteins binding to the 5' UTR, which prevents ribosomes from attaching.

What type of enzyme is nuclease?

A hydrolytic enzyme -- performs hydrolysis to separate/break up molecules.

What happens if a protein does not fold into its proper conformation (shape)?

Ubiquitin tags the damaged protein, which tells it to go inside a proteasome (a protein complex that contains hydrolytic enzymes). Once inside, the enzymes will degrade it.

What do chaperone proteins do?

Provide a suitable/adequate environment for damaged proteins to refold.

What is cell development?

The growth and transformation from a zygote to an adult via cell division, cell differentiation, determination, and morphogenesis.

In cell development, what is cell division?

Mitosis.

In cell development, what is cell differentiation?

The process cells undergo to become specialized in structure and function.