Bio Unit 5 - DNA & Mitosis

Chargaff's Rule

Adenine always pairs with Thymine & Guanine always pair with Cytosine

What is the shape of DNA?

double helix (twisted ladder) with sugar-phosphate backbones

What holds base pairs together?

hydrogen bonds

DNA (what does it stand for?)

Deoxyribonucleic acid.

What is the function and location of DNA?

Contains genetic information for chromosomes. In Eukaryotes it is in the nucleus and in cytoplasm for Prokaryotes.

3 parts of DNA

Nucleic acids (polymers) are made up of: Sugar (deoxyribose), phosphate, nitrogenous base ( 4 different choices (ATGC))

Purines

Adenine and Guanine who each have 2 rings of carbon and nitrogen

Pyrimidines

Cytosine and Thymine (Uracil for RNA) and have a single ring of carbon and nitrogen

What type of bonds hold the phosphate and sugars in the ladder sides of DNA?

Covalent bonds

What type of bond does Adenine have with Thymine?

Double bond

What type of bond does Cytosine have with Guanine

Triple bond

What is DNA replication?

When DNA copies its code into another DNA molecule. Cells divide so each cell has a complete DNA

1st step of DNA replication

1. The DNA "unzips" by helicase and the two strands separate

2nd step of DNA replication

Strands are kept separated with "clamps" at replication with single strand binding proteins

3rd step of DNA replication

Elongation: new complementary bases are added, by using DNA polymerase

Helicase

The enzyme the breaks the hydrogen bonds between the nitrogen base pairs. Part of the 1st step of DNA replication

Replication Fork

y-shaped region where the parent DNA strand splits into two separate strands

leading strand

runs in 5' 3' direction, does not require ligase and runs in the direction of the replication fork, grows fast, there is only one primer

lagging strand

Runs in the 3' 5' direction, short fragments are formed during synthesization known as Okazaki fragments. Each fragment requires its own set of primers. Ligase is required every time Okazaki fragments form. Grows in the opposite direction of the replication fork

DNA polymerase

Enzyme that joins individual nucleotides to produce a DNA molecule (polymer). It is transforming a monomer into a polymer. It also proofreads to make sure all of the base pairs are correct

DNA ligase

An enzyme that glues the nucleotides together. Helps form hydrogen bonds of the newly formed nitrogen base pairs of the daughter cell

What is transcription

Takes place in the nucleus makes mRNA from DNA

How many chromosomes do humans have?

46 (23 pairs)

What are the differences between DNA and RNA?

DNA has thymine whereas RNA has Uracil. DNA sugar is deoxyribose and RNA sugar is ribose. DNA is double stranded and RNA is single stranded. DNA is only in the nucleus, whereas RNA can travel between the cytoplasm and nucleus. There is only one type of DNA and there are three types of RNA

Mitosis (PMAT)

part of eukaryotic cell division during which the cell nucleus divides

Interphase

Growth before mitosis. DNA starts replicating and other cell parts replicate. There is a G1, S, G2 phase

Prophase

Chromosomes condense, the nuclear membrane dissolves, centrioles move to opposite ends of cells

Centrioles

Cylindrical organelle, near nucleus of animal cells and help with the development of spindle fibers

Metaphase

In the middle, where the chromosomes will start to line up and the spindle fibers attach to the centromere

Anaphase

Sister chromatids start to spread apart, and are pulled to opposite ends of the cell

Telophase

The cell will form 2 nuclear membranes around the chromosomes, cell wall begins to pinch and have contractile ring

Cytokinesis

The cytoplasm of the parent cells and other cell parts separate to form 2 new daughter cells with the same genetic information

Chromosomes

Threadlike structures made of DNA and protein, that become coiled and condensed forming and X shape, contains the genetic information for an organism. It is condensed during mitosis

Centromere

Links a pair of sister chromatids, it is the constricted region of a chromosome

Chromatin

Spaghetti like strands of non-condensed DNA and protein that are in the nucleus of a non-dividing cell. Histone proteins will then help it coil to fit inside of a nucleus

Sister Chromatid

2 identical chromosomes are a result of DNA replication, they are separated during mitosis

Diploid

2 versions of each chromosome that are not identical, one from each parent

Haploid

1 version of each chromosome

RNA primase

Primer on the DNA strand to tell polymerase where to start building

DNA polymerase

It builds new daughter strands that are complementary by adding nucleotides in the 5' 3' direction

Nucleotides

Monomer of DNA. Consists of phosphate group, deoxyribose sugar and a nitrogenous base

Semi conservative model

After DNA replication, one strand is a parent strand and the other is the newly synthesized strand

Binary fission

Asexual reproduction by the separation of one body into two bodies. Amoeba and bacteria both undergo it

Synthesis phase of interphase

Where a cell replicates it's DNA making an exact copy in preparation for mitosis