Chapter 4 - Genetics and Cellular Function Flashcards
What do the nucleotides in DNA consist of?
A sugar, phosphate group, and nitrogenous base
What is DNA?
A polymer of nucleotides
What are the nitrogenous bases?
Cytosine (C), thymine (T), adenine (A), and guanine (G)
What is DNA described as?
A double helix that resembles a spiral staircase
What is each side piece composed of?
Phosphate groups alternating with deoxyribose (sugar)
What is the essential function of DNA?
To carry instructions for the synthesis of proteins
What does RNA consist of?
Only one nucleotide chain
What are the types of RNA?
a) mRNA- the molecule that carries the genetic code from the nucleus to the cytoplasm.
b) tRNA- binds a free amino acid and delivers it to the ribosome.
c) ribosome- the molecule that “reads” the mRNA.
What is a gene?
An information-containing segment of DNA that codes for the production of a molecule of RNA
What is a genome?
All the DNA in a set of 23 pairs of chromosomes
What happens in protein synthesis?
- Transcription
- Translation
- Termination
What is Transcription?
The process of copying genetic instruction from DNA to a complementary RNA
What is Translation?
The process of reading the mRNA an synthesizing the protein encoded in the nucleotide sequence
What happens during Initiation?
i) mRNA outside the nucleus forms a loop.
ii) The ribosomal subunits and the initiator tRNA bind to the mRNA.
iii) The ribosome begins sliding along the mRNA reading bases.
What happens during Elongation?
i) The tRNA that matches the next sequence on the mRNA binds to the ribosome.
ii) The amino acid from the previous tRNA binds to the new amino acid on the new tRNA.
iii) The ribosome slides over the mRNA and the previous tRNA leaves the ribosome.
What is Termination?
The ribosome reaches the stop sequence on the mRNA and releases from the mRNA
What happens in DNA Replication?
- The double helix unwinds.
- The enzyme DNA polymerase moves along the strand, reads the exposed base and arranges a match with complementary free nucleotides.
- Each old (parental) strand has a new (daughter) complementary strand resulting in two identical copies of daughter DNA.
What are the functions of Mitosis?
a) Development of an individual.
b) Growth of tissues and organs after birth.
c) Replacement of cells.
d) Repair of damaged tissue.
What are the phases of Mitosis?
a) Prophase
b) Metaphase
c) Anaphase
d) Telophase
What happens during Prophase?
i) Chromosomes coil into compact rods which consist of two identical sister chromatids.
ii) The nuclear envelope disintegrates.
What happens during Metaphase?
The chromosomes align at the cell equator
What happens during Anaphase?
Sister chromatids are pulled apart to opposite poles of the cell
What happens during Telophase?
i) A new nuclear envelope forms around the chromatids.
ii) The chromatids uncoil.
What is Cytokinesis?
Division of the cytoplasm into two cells
