Biology Unit 2 - Codes

Includes DNA function, chromatin and chromosomes, gene function, karyotypes, and abnomalities

DNA stands for…

deoxyribonucleic acid

In eukaryotes, the DNA is located in…

the nucleus, organelles, chloroplasts, and mitochondria

DNA floats freely in…

prokaryotes

DNA "talks" with the rest of the cell using…

messenger RNA/mRNA (other types of RNA used by DNA are involved in protein synthesis and regulation).

Nitrogenous bases are…

adenine, guanine, thymine, and cytosine

List the Purines (Double carbon-nitrogen ring):

Adenine and Guanine

List the Pyrimidines (Single carbon-nitrogen ring):

Thymine (DNA only) and Cytosine

What are the (Nitrogenous) Base pairing rules?

A pairs with T and G pairs with C

How do DNA strands run?

They run opposite of each other in a double helix (anti-parallel)

Nucleotides (DNA monomers) are made up of…

a 5-carbon sugar, a phosphate base, and one of 4 nitrogenous bases (A, C, T, G)

The 3' end of a nucleotide needs which functional group to have a full valence shell (be stable)?

OH

Where is the 5’ end of a nucleotide?

It is bonded outside the ring and attached to the phosphate group.

Does DNA do anything on its own?

No - it’s the recipe book for the genes (recipes)

Polymerization is…

the creation of molecular chains from smaller units. The chain is called the polymer and the subunits are called monomers

Dehydration synthesis is…

a special type of polymerization that takes two monomers with the functional groups H and OH respectively, bonds the two together, and releases H2O. (A+B = A-B and H2O)

Hydrolysis is…

the reverse of DHS: the breakdown of the water to break the polymer chain.

Chromatin is…

DNA wrapped around histones (a type of protein) and the form DNA usually takes before mitosis or meiosis.

Chromosomes are both…

a long, tightly-packed strand of chromatin or two of these packages

In a chromosome, the singular chromosome is the same as the other and comes from the same parent. We call these single chromosomes…

sister chromatids

Two chromosomes (that are doubled and joined at the centromere) are homologous when…

they have the same genes but come from different parents

The ends of the chromosomes are called…

telomeres

The centromere is…

the center of the point where two sister chromatids are joined. It keeps chromosomes (one chromatid) aligned during cell division.

Nucleosomes are…

DNA wrapped around histones not joined with linker DNA

Chromosomes (two chromatids) that have their centromere near the center and equal-sized p and q arms are called…

Metacentric chromosomes

Chromosomes (two chromatids) that have their centromere closer to one side and a p arm just a little shorter than the q arm are called…

Submetacentric chromosomes

Chromosomes (two chromatids) that have their centromere nearest to one side, a short p arm, and a long q arm are called…

Acrocentric chromosomes

Chromosomes (two chromatids) that have their centromere at the end of the chromosome and just a q arm (p arm so short - not real)

Telocentric chromosomes

Scientists indicate the location of a gene using…

the chromosome number and the arm of the chromosome (E.g. - 17p12 is the 12 location on the 17th chromosome's p arm)

Genes used two program functional products called…

RNA and protein

We can't sequence DNA from a protien because…

the proteins are only programed with exons (missing base introns sequence).

Chromosomes’ (chromatids) two types of areas are…

heterochromatin and euchromatin

Heterochromatin is…

tightly wrapped, and genes here can't be accessed (silent)

Euchromatin is…

less tightly wrapped, and genes can be accessed here. (active)

The genome is….

an organism’s complete set of DNA: exons + introns, functional groups (regulatory sequences), junk DNA (DNA with no clear function)

Sequencing is…

The process of determining the order of the nucleotides (bases, AGCT) in DNA.

The first non-bacterial genome to be sequenced was…

yeast (Saccharomyces cerevisiae)

Exons are…

coding DNA segments for amino acid sequences of proteins found in both prokaryotes/eukaryotes whose sequences are highly conserved (retained in product)

Introns are…

DNA segments that are non-coding, serve as the base between to exons, found only in eukaryotes (?), and sequences are less conserved (not retained in product)

Non Coding DNA is…

DNA composed of introns that doesn’t code for proteins but is important for controlling gene activity, accounts for 99% of the human genome, and undergoes transcription to synthesize most RNA types (excluding mRNAs).

Coding DNA is…

DNA composed of exons that codes for proteins (that have structural, functional and regulatory importance), accounts for 1% of the human genome, and undergoes transcription to synthesize mRNA.

Humans have around ____ bill. base pairs (A, C, T, G), up to __ coding genes (many base pair sets), and __ proteins

3, 25,000, 100-150,000

Do we have more proteins than genes?

yes

Scientists use model organisms to…

run tests on genes shared with humans to preform research

Phenotypes are…

the observable traits associated with a gene

Phenotypic plasticity describes…

the ability of a phenotype to change based on its environment and a gene’s ability to turn on and off

How can we control genes?

By controlling the rate of transcription, RNA processed, or mRNA sent out

A typical karyotype has…

46 chromosomes (two chromatids joined together near mitosis/meiosis)

To create a karyotype, geneticists use _________ dye to create a zebra-like pattern: the heterochromatin is dyed _____ and the euchromatin _____.

Giemsa, black, stays white

Geneticitst pair chromosomes by…

length and chromatin markings

Aneuploidies are…

karyotype abnormalities when a person is missing or has too many chromosomes.

Trisomy describes…

a karyotype that has one too many chromosomes.

Monosomy describes….

a karyotype that has one chromosome too few.

A Monosomy is worse than a trisomy because…

the genetic information is missing. Always results in the death of a fetus/infant.

Terminal deletion is….

the breakage of one end of a chromosome/ the deletion of nucleotides from the terminal end of a DNA molecule

Write the proper notation for a male karyotype with 46 chromosomes.

(Normal) 46 XY

Write the proper notation for a female karyotype with 45 chromosomes (missing a sex chromosome).

Monosomy 45 X0

Write the proper notation for a male karyotype with 47 chromosomes (additional 21 chromosome)

Trisomy 47 XY +21

The sex chromosomes are ____ and _____. Females typically have ___ and males typically have _____.

XX, XY, XX, XY