Cell Biology 2: DNA Replication and Protein Synthesis (mostly)

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Plasma Membrane

separates cell from external environment; controls passage of organic molecules, ions, water, oxygen, and waste into and out of the cell

Phospholipid

hydrophilic head, hydrophobic tail

Nucleus

organelle that houses DNA

Nucleolus

assembles ribosomes using ribosomal RNA (rRNA) and other proteins

Nuclear Envelope

double layer membrane surrounding the nucleus

Nuclear Pore 

membrane structure that allows for the selective passage of macromolecules (like RNA) and proteins needed for cellular processes

Chromosome

condensed DNA and proteins

Chromatin

uncondensed DNA that looks like threads

Histones 

protein DNA wraps around 

Genome

the complete set of DNA in an organism

Extracellular Matrix

network of non-cellular components that support cells and tissues; outside of a cell

Tight Junctions 

watertight seal between 2 adjacent animal cells; proteins hold the cells tightly against each other 

Desmosomes

keeps cells together and allows for stretching

Gap Junctions

tunnels between cells

What are the structures associated with DNA?

the nucleus and nucleoid

What types of bases are found in DNA?

adenine, guanine, cytosine, thymine (AGCT)

What does adenine pair with?

Thymine

What does cytosine pair with?

Guanine

What bonds connect the strands of DNA?

Hydrogen bonds

What does it mean to have a fluid-mosaic type of cell membrane?

To have many components to a cell membrane

Where does DNA replication take place?

Nucleus

When does DNA replication happen? 

Before the cell divides; interphase 

What is an enzyme?

protein that speeds up reactions 

What is the first step of DNA replication?

Helicase (enzyme) unzips DNA by breaking through hydrogen bonds; Initiation

What is the second step of DNA replication?

Primase (enzyme) makes primer (made of RNA) to provide a starting point for the DNA polymerase; Priming 

What is the third step of DNA replication?

DNA polymerase (enzyme) matches up the correct bases to each other; Elongation 

What is a genome?

complete DNA of an organism

What is a gene?

Segment of DNA that provides instructions for a cells function; unit of heredity

What is RNA?

Single-stranded nucleic acid 

What are the bases for RNA?

Adenine, Uracil, Guanine, Cytosine (AUGC)

What pairs with adenine? (RNA)

Uracil

What is the first step of protein synthesis? 

Helicase unzips the DNA into 2 strands; Transcription

What is the second step of protein synthesis?

RNA polymerase attaches to the DNA at the promoter; Transcription

What is the third step of protein synthesis?

RNA polymerase makes mRNA by basing it off the DNA; Transcription

What is mRNA?

Messenger RNA; single stranded nucleic acid that carries code for a single gene

What is the fourth step of protein synthesis?

RNA polymerase reaches a stop codon and releases the mRNA from the DNA; Transcription 

What is the fifth step of protein synthesis?

mRNA travels to a ribosome; Translation

What is rRNA?

Ribosomal RNA; makes up ribosomes 

What do ribosomes make?

Protein

What is the sixth step of protein synthesis?

tRNA binds to the mRNA, according to the mRNA’s message; Translation 

What is tRNA?

Transfer RNA; carry an amino acid on them

How does tRNA bind to mRNA?

In triplets; codon

Anticodon

Complementary base on tRNA

What is the seventh step of protein synthesis?

tRNA leaves to get another amino acid and the amino acids left behind link together and form a peptide bond between each other; Translation 

What is the eighth step of protein synthesis?

Amino acids form a polypeptide chain; Translation

What is the ninth step of protein synthesis?

Ribosome reaches a stop codon on mRNA and releases polypeptide chain; Translation

When does translation happen?

After the mRNA leaves the nucleus