• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

Card Range To Study

through

image

Play button

image

Play button

image

Progress

1/15

Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

15 Cards in this Set

  • Front
  • Back

What is the structure of DNA, where is DNA found & what is DNA made up of?

*Double helix structure.



*Found in all cells except red blood cells.



*Made up of 4 bases.


How is DNA adapted?

*Stable molecules



*Hydrogen bonds which break easily



*Large structure = Lots of information



*Not easily corruptible structure

When & why does DNA replicate itself?



What breaks the hydrogen bonds in DNA?

*Just before mitosis when the cell divides.



*To pass on information so the cell can make an exact copy of itself.



*Helicase breaks hydrogen bonds.

What is the structure of a nucleotide unit?

*A phosphate - Phosphoric acid



*A sugar - Deoxyribose in DNA



*1 of 4 organic bases - Adenine, Guanine, Cytosine & Thymine {always contains Nitrogen & Carbon}.

What are nucleic acids made up of?

*Polymers



*Individual unit - {Mono}nucleotide



*DNA is a type of nucleic acid.

What are purines and give examples of them?

*Double ringed structure
 
*Adenine
 
*Guanine

*Double ringed structure



*Adenine



*Guanine

What are pyrimidines and give examples of them?

*Single ringed structure
 
*Thymine
 
*Cytosine

*Single ringed structure



*Thymine



*Cytosine

What are the two bonds in DNA, how do they occur & what are the pairing of the bases?

*Base + Sugar - Glycosidic bond.



*Phosphate + Sugar - Ester bond.



*Condensation reaction is needed.



*Purines pair with pyrimidines - Adenine joins to Thymine & Cytosine joins to Guanine.

How much amino acids occur naturally, what is a triplet code & how many different combinations in triplet codons can be formed?

*There are 20 naturally occuring amino acids.



*Triplet code is a sequence of 3 bases coding for a specific amino acid.



*4 bases -> 64 different combinations in triplet codons.

Outline the first nuclear division of meiosis?

*Interphase I - Chromatin not visible & DNA & proteins replicated.


*Prophase I - Chromosomes visible, homologous chromosomes join to form a bivalent & chromatids cross over.


*Metaphase I - Bivalents line up on equator.


*Anaphase I - Chromosomes separate.


*Telophase I - Nuclei form, cell divides & have 2 chromosomes.

Outline the second nuclear division of meiosis?

*Interphase II - Short, no DNA replication & chromosomes remain visible.


*Prophase II - Centrioles replicate & move to new poles.


*Metaphase II - Chromosomes line up on equator.


*Anaphase II - Centromeres split & chromatids separate.


*Telophase II - 4 haploid cells, 2 chromosomes each & cells usually stay together to form tetrad.

What is a gene, locus & allele?

*Gene - A section of DNA that codes for a polypeptide.



*Locus - The position of a gene on a chromosome or DNA molecule.



*Allele - One of the different forms of a particular gene.

What are the two ways in which meiosis brings about genetic variation?

*Independent segregation of homologous chromosomes.



*Recombination of homologous chromosomes by crossing over.

Explain independent segregation of homologous chromosomes.

*During the first division, the chromosomes line up along its homologous partner.


*They randomly place themselves in line.


*1 pair of each will be passed on to each daughter cell.


*The pair which goes in to each daughter cell depends on how the pairs are lined up.


*Since the pairs lined up randomly, the combination of chromosomes is random.

Explain genetic recombination by crossing over.

*During meiosis I, chromosomes line up alongside its homologous pair.


*The chromatids of each pair become twisted around one another.


*The twisting process causes tension and portions of chromatids break off.


*Broken portions rejoin with the chromatids of their homologous partner - recombination.


*Usually equivalent portions are exchanged - crossing over.