Exam 3 Bio

How does UV light and other ionizing radiation damage DNA molecules?

creating thymine dimers between adjacent thymines in the DNA chain.

Which of the following synthesizes the new DNA strand?

DNA polymerase

A carcinogen is a chemical or treatment that

causes mutations that increases the likelihood of developing cancer.

Oncogenes and tumor-suppressor genes have the shared property that

when either type of gene is mutated, cancer can result.

Which of the following could not result from mutations?

a fish in a stream dies from a poison that blocks cellular respiration

The parts of chromosomes where the spindle apparatus will attach are called

centromere

When a single chromosome has undergone DNA replication, it consists of two

sister chromatids

The human (blank) consists of 23 pairs of chromosomes.

Genome

Each pair of human chromosomes (for example, two copies of chromosome 17) is called a pair of

homologous chromosomes

The phase is when most cell growth will occur; DNA is unreplicated.

G1 phase

During (blank) phase, the genetic material undergoes replication.

S (synthesis)

During (blank) phase occurs between chromosome replication and mitosis.

G2 phase

During (blank) phase, the shortest phase, the cell undergoes both nuclear division (mitosis) followed by cell division (cytokinesis).

M

cytokinesis events

Animals - cleavage furrow

Plants - cell wall and cell plate

Both - two daughter cells formed after cytokinesis and mitosis completes right before cytokinesis.

The division of the cytoplasm is called

cytokinesis

Mitosis, followed by cytokinesis, results in the formation of two genetically identical daughter cells. This is because

all the genetic material is duplicated then segregated equally to the daughter cells.

During prometaphase, the sister chromatids organize into a single row in the center of the cell

False

Mitosis produces_________, and meiosisproduces_________ cells

two haploid, 4 haploid

In mitosis, the main difference between plant and animal cells is that

plants produce a cell plate to segregate the daughter nuclei, while animals form a cleavage furrow

Which check point prevents cells from incorrectly sorting their chromosomes during cell division?

Metaphase Checkpoint

Chromosomes are replicated during the_________ phase

S

What is DNA?

genetic material that provides the blueprint to produce an individual’s traits.

How do we read DNA sequence?

5’ to 3’

Chargaff Rule

A = T and G = C

Hydrogen Bonding (Double Helix) of DNA

hydrogen holds the two strands together

The two strands are known as a double helix

Antiparallel

Guanine and Cytosine are going to have

3 bonds

Thymine and Adenine will only have

2 bonds

Matched pairs are called

complimentary

Central Dogma

DNA → mRNA —> Protein

Transcription → Translation

Semiconservative

A newly formed DNA molecule has one new strand and one strand from the original DNA.

What is a primer?

A primer is how a new strand can be created.

The template will read from 3’5 and then be synthesized from 5’ to 3’.

Procaryotes have

two identical daughters

Eukaryotes

are much longer

DNA proteins

Helicase

Single-Stranded Binding Proteins

Topoisomerase

DNA primase

DNA pol III

Clamp protein

DNA pol I

DNA ligase

Helicase

unwinds and separates the two strands of DNA into single-stranded templates

Single-Stranded Binding Proteins

stabilize the single-stranded DNA so it doesn’t re-anneal (reattach)  right behind helicase

 Topoisomerase

•relieves twisting stress so that the double-stranded DNA does not knot up as helicase unwinds it. Does this by nicking one strand, letting the structure unwind, and then ligating the strand back together.

DNA primase

makes RNA primer

DNA pol III

synthesizes the new DNA strand, starting at the open 3’ end of the primer

Clamp protein

Holds DNA pol III on the template and slides from 3’ to 5’

 DNA pol I

Replaces the RNA primer with DNA

DNA ligase

Attaches two adjacent fragments of new DNA together.

What is DNA polymerase?

Replicates most of the DNA during cell division, removes RNA primers and fills in the gaps, and then repairs damaged DNA and replicates over DNA abnormalities.

In other words, it is a type of enzyme that is responsible for forming new copies of DNA, in the form of nucleic acid molecules.

Okazaki Fragments

lagging strand

Telomere

Telomeres are made by an enzyme called telomerase.

Telomeres are made to stabilize the DNA molecule.

Heterochromatin

densely packed, inaccessible DNA. The DNA is also protected in this form

euchromatin  

loosely packed, accessible DNA. Exposed, and more subject to damage.

transcription

the sequence of bases in DNA is used to code for a complementary strand of RNA.

Translation

The sequence of bases in mRNA is used to code for a sequence of amino acids

Genetic code

The set of rules by which DNA sequences are used to make proteins in living things.

mRNA

messenger, used to code for the sequence of amino acids in protein during translation.

tRNA

transfer, used during translation.

what is pre mRNA

the primary transcript in the transcription process.

How does transcription occur?

Initiation, elongation, and termination.

RNA polymerase begins by binding to a promotor sequence (“upstream” )to the 3’ end of the template strand) of the gene to be transcribed.

RNA polymerase

Synthesizes RNA by following a strand of DNA.

What is a promoter and what does it do?

A promoter contains DNA sequences that let RNA polymerase or its helper proteins attach to the DNA.

What are RNA complementary bases?

A-T

C-G

Intron

have a role in RNA processing and can contribute to the ability to form more than one polypeptide from a single gene.

Exons

a pre-mRNA transcript contains exons, which will code for protein.

Spliceosome

contains protein and snRNA

this is done in the nucleus

Start codons and stop codons

Start - AUG

Stop - UAA, UAG, and UGA

what is an anticodon?

The complementary to the DNA strand.

Operons

Prokaryotic genes are organized into structures.

What is the basic structure of an operon

contains a promoter, an operator, and a coding sequence.

What is a repressor?

proteins that turn off or reduce gene expression.

Activator

increases transcription of a gene or set of genes

What is cancer?

a disease caused by gene mutations

Mutation

A heritable change in the genetic material

germ mutations

are changes to your DNA that you inherit from the egg and sperm cells during conception.

Somatic mutations

Are changes to your DNA that happen after conception to cells other than the egg and sperm.

Coding Mutations

Leu: CUU, CUC, CUA, CUG

Pro: CCU, CCC, CCA, CCG

Are spontaneous mutation random?

Yes

Germ-line cells

gives rise to gametes

Mutation can occur in sperm or egg cell, or in gamete progenitor cells

passed on to offspring.

Somatic cells

are all other body cells

can occur early or late in development

gives a genetic mosaic with patches of mutant tissue.

What is Direct Repair?

A repair enzyme recognizes an incorrect structure in the DNA and directly restores the correct structure.

Uvr damage

radiation causes several types of DNA damage, one of which is a thymine dimer (two cross-linked T’s) and the repair systems comes in to fix it.

P53 where does it happen and what does it do?

happens in the cell cycle. (G1)

It is a tumor repressor that stops cell’s cycle here if DNA damage is detected.

What is an oncovirus

cancer causing viruses.

Mitosis

is the division of a cell to form genetically identical daughter cells.

•For growth, development, or tissue renewal

Meiosis

is the division of a cell to form gametes with ½ of the genetic material.

•Forms gametes, or germ cells

cytokinesis

cell division which divides the cytoplasm of a parental cell into two daughter cells.

Plants and animals are different.

Interphase

the period of cell growth

G1 and G2

Gap (growth phases)

S

synthesis phase is where DNA is replicated

5 stages of Mitosis

Prophase

Prometaphase

Metaphase

Anaphase

Telophase

Cyclins

proteins that advance the cell cycle

Humans have 22 pairs of…

autosomes (non-sex chromosomes)

Humans have one pair of

sex hormones

Sister chromatins

Are identical to each other with associated proteins.

Centrosomes

–Microtubule organizing center (M T O Cs)

–Duplicates during interphase

•Each defines a pole

Microtubules

The miotic spindle organizes and sorts the chromosomes during mitosis.

Phases of Mitosis

G2 of interphase

Prophase

Prometaphase

Metaphase

Anaphase

Telophase

Cytokinesis

In cytokinesis animal and plant cells differ how?

•Animal cells: a cleavage furrow forms, which splits the cell.

•Plant cells: vesicles form a cell plate (new cell wall and membrane) that expands and splits the cell.

Asexual

clones

Sexual

genetic diversity

Haploid

Single set of chromosomes

Diploid

two complete sets of chromosomes

bivalent

•Homologous pairs of chromosomes brought together into a bivalent (this is called synapsis). - Allows crossing over and genetic variability.

Meiosis has how many haploid cells?

4