Biology Final Flashcards
What are the four types of nitrogenous bases? How do they pair together?
Adenine—>Thymine.
Cytosine—> Guanine.
What are the three structures that make up a DNA strand?
A nitrogenous base, deoxyribose sugar, and a phosphate group.
What type of bond connects the nitrogenous bases together?
A hydrogen bond.
What type of bond connects the deoxyribose sugar and the phosphate group together?
A covalent bond.
What does 5’ connect to and what does 3’ connect to?
5’ connects the 5th carbon atom to the phosphate group, and the 3’ connects the 3rd carbon atom to the hydroxyl group.
DNA molecules run ____ from one another.
antiparallel.
How many chromosomes does each human have per cell?
46 chromosomes, 23 pairs.
What connects the deoxyribose sugars together?
A phosphate group
What happens to the DNA when it makes a copy of itself?
When the heavy DNA makes a copy of itself, it gets lighter.
How does the leading strand copy?
The leading strand copies continuously towards the replication fork 5’ to 3’.
How does the lagging parent template copy?
The lagging parent template copies 3’ to 5’ away from the replication fork.
What is the first step of the DNA replication process?
The enzyme Helicase breaks H bonds between the Nitrogenous bases.
New strands are extended at the replication fork in both directions.
What is the second step of the DNA replication process?
Primase works to identify the location of the gene where DNA polymerase is to replicate.
DNA Polymerase helps to attach the new nucleotides as they align with their base pair in the 5’ to 3’ direction.
What is the third step of the DNA replication process?
Lagging strands (Okazaki fragments) extend in pieces away from the replication fork. The enzyme, DNA ligase attaches the fragments on the lagging strand into one piece.
What are histones?
Protein molecules whose DNA is tightly coiled.
What are the four enzymes used for DNA replication?
Primase, Ligase, DNA polymerase, and helicase.
What is insertion? What is deletion? What is substitution?
When a base is added. When a base is deleted. When a base is changed or substituted.
What type of mutation does insertion and deletion cause?
Deletion and Insertion may cause what’s called a frameshift mutation, meaning the reading ”frame” changes, thus changing the amino acid sequence from this point forward.
What types of mutations does substitution cause?
Causes missense, nonsense, or a silent mutation.
What is a silent mutation?
When only one codon is changed, it doesn’t affect the amino acid.
What is a missense mutation?
When the codon(s) are changed, and the amino acid is affected.
What is a nonsense mutation?
The codon changes the amino acid to a “stop” codon before the sequence is finished.
What are the four bases of RNA?
Adenine-Uracil Cytosine-Guanine
What is the definition of DNA versus RNA?
DNA has the genetic codes to control cell activities and create proteins.
RNA copies and translates genetic codes to build these proteins.
What is mRNA?
Stands for messager RNA. Copies the genetic code from DNA and carries it to the ribosomes to create proteins.
What is tRNA?
Stands for transfer RNA. Shaped like a T. Transfers specific amino acids by carrying them to the ribosome for protein synthesis.
What is rRNA?
Makes up ribosomes. Holds mRNA in place at the ribosome and catalyzes peptide bond formation.
What is transcription?
Making an mRNA copy of a gene on DNA in the nucleus.
What is translation?
Turning the copied mRNA into protein by decoding the mRNA at the ribosome.
What is a codon?
Three mRNA bases= 1 codon
Each codon= 1 amino acid
What is an anti-codon?
3 nucleotides sequence complementary to the codon in an mRNA sequence.
Found at one end of a tRNA molecule.
List the four steps of cell division.
G1, Synthesis, G2, Mitosis
What steps are part of the interphase?
G1, Synthesis, and G2.
Explain what happens during each phase of the Cell Cycle.
In G1- The cell begins to grow
S phase- DNA is replicated
In G2- The cell grows even more and completely develops. Prepares for cell division.
Mitosis- The cell is divided into two daughter cells.
What are the different types of cell reproduction?
Sexually: Offspring is a combination of two parents.
Asexually: Offspring is identical to its single parent.
What parts of the Cell Cycle is interphase?
Interphase is not part of mitosis-it is the time between cell division. Interphase includes G1, S, and G2.
What are the three steps of prophase?
- Mitosis begins. Chromatin is condensed into chromosomes.
- Centrioles form spindle fibers and begin to move to opposite ends of the cell.
- Nuclear membrane breaks down and disappears.
What are the two steps of Metaphase?
- Chromosomes attach to the spindle fibers and line up at the equator (middle) of the cell, the metaphase plate.
- Spindle assembly checkpoint: perfect chromosome separation can be guaranteed.
What are the two steps of anaphase?
- The sister chromatids separate at the centromeres.
2. Each chromatid heads to opposite poles of the cell.
What are the three steps of telophase?
- New nuclear membranes start to form around the DNA.
- The chromosomes begin to decondense back to chromatin.
- Cytoplasm begins to pinch in animal cells forming a cleavage furrow and a cell wall begins to form in plant cells- this is cytokinesis.
What do different checkpoints check for?
G1: The cell needs to have grown big enough.
G2: There can be no errors in DNA replication.
Middle of Mitosis (metaphase): DNA needs to be lined up evenly.
What is cancer?
Cancer is uncontrolled cell growth. They form in tumors of masses of abnormal cells.
What are the two steps of interphase?
- Interphase is the stage of growth and preparation. 2. Chromosomes are copied (# doubles) and appear as threadlike unorganized coils, called chromatin, at first.
What is diploid?
Two complete sets of chromosomes, one from each parent.
What is a haploid?
One of each chromosome.
What is a gamete?
Sperm or egg cell, gametes are haploid.
What is fertilization?
The process of one male (sperm) gamete and one female (egg) gamete coming together.
What is a zygote?
A cell formed when two gametes come together.
How many divisions and DNA are in meiosis?
Two divisions, 1/2 DNA in each of the four cells, are four the cells are genetically different.
What is a somatic cell?
Any other cell other than reproductive cells.
What happens during prophase I?
- Mitosis begins. Chromatin is condensed into chromosomes.
- Centrioles form spindle fibers and begin to move to opposite ends of the cell.
- Nuclear membrane breaks down and disappears.
- Crossing over occurs.
What is crossing over?
Homologous Chromosomes exchange genetic information to create genetic diversity in gametes.
What are homologous chromosomes?
Homologous chromosomes are chromosome pairs (same number and length).
What happens during metaphase I?
- Homologous Chromosomes attach themselves to spindle fibers.
- Homologous Chromosomes align randomly at the equator as pairs.
- Results in new genetic combinations/variations in gametes and therefore, offspring; greater genetic diversity.
What happens during anaphase I?
- Homologous Chromosomes move apart to opposite poles once attached to spindle fibers (in metaphase).
What happens as an end result of telophase I?
- The end result after cytokinesis is two cells with sister chromatids remaining to be separated.
Does DNA replicate again before meiosis II?
No, DNA doesn’t replicate itself a second time.
What happens during prophase II?
- Chromatin is recondensed into chromosomes.
- Centrioles form spindle fibers and begin to move to opposite ends of the cell.
- Nuclear membrane breaks down and disappears.
What happens during metaphase II?
- Chromosomes attach to the spindle fibers.
2. Sister chromatids randomly line up along the metaphase plate like regular mitosis.
What happens during anaphase II?
- During Anaphase II, centromeres break and each sister chromatid is pulled to opposite sides of the cell.
What happens during Telophase II?
- The two cells split off, end result is 4 gamete cells that are genetically different from each other.
What are inherited mutations?
Inherited mutations are when mutations are passed from a parent onto an offspring. All of the offspring’s cells will carry the mutation.
What are new mutations in the germline?
New Mutations in Germline are when a mutation associated with a disease occurs during gamete production. The offspring can inherit the mutation from an unaffected parent.
What are somatic cell mutations in development?
The development of specific tissues and organs in the body can be affected by somatic cell mutations that occur early in life. Are inherited by a parent.
What are somatic cell mutations later in life?
Cancer can result from somatic cell mutations that occur later in life. Are inherited by a parent.
What are proto-oncogenes?
Proto-oncogenes normally function to accelerate cell growth/division.
What happens when proto-oncogenes are mutated?
If they’re mutated, they become oncogenes and accelerate cell division and growth way too quickly out of control.
What are tumor suppressor genes?
Tumor suppressor genes act to slow down cell division, repair DNA mistakes, and tell cells when to die.
What happens when tumor suppressor genes are mutated?
When mutated, they can cause cells to grow out of control which can lead to cancer.
What are DNA repair genes?
Normally functions to fix minor damages to DNA when the replication isn’t perfect.
What happens when DNA repair genes are mutated?
When tumor suppressor genes are mutated, this can lead to cancer because the replication damages aren’t fixed.
How do proto-oncogenes relate to a gas pedal?
Proto-oncogenes are similar to a gas pedal, helping cells grow and divide at a faster rate. When this gas pedal breaks, this causes the cells to divide uncontrollably.
How do tumor suppressor genes relate to a brake pedal?
Tumor Suppressor Genes are similar to a brake pedal. Keeps cells from dividing too quickly, just as a brake keeps a car from going too fast.