Chapter 2: The Structure of Genetic Material - Biology

Question 1

DNA

Answer 1

• Conain the code, and instructions for building an organism ensuring that it functions properly, and correctly
• Most of the cell cycle, it is found as the chromatin fibre
• During mitosis, chromatin fibre condenses into chromosomes

Question 2

Gene

Answer 2

A segment of DNA which codes the protein which in turn codes a specific trait such as skin tone, eye colour etc..A gene is a stretch of DNA

Question 3

DNA Overall Shape and Structure

Answer 3

• It’s shape is like a double helix (a twisted ladder)
• An individual strand of DNA is known as a nucleotide
• Nucleotides are made up of a phosphate group, a sugar group, and a base
• Think of a row in the DNA, there are two nucleotides in that row. The walls of the DNA is the sugar phosphate, and one block of sugar phosphate connects to one block of base which is what is a nucleotide. It connects to another pair of nucleotide at another side.

Question 4

DNA Structure (more of the chemical pairings)

Answer 4

• The sides of the ladder are composed of alternating sugars (deoxyribose), and phosphates
• The blocks or rungs of the ladder are composed of the following bases (Adenine, Thynine, Guanine, Cytosine: THINK OF ATGC AS AN ACRONYM)
• Nucleotides create a pair in a specific way under the Base-Pair rule to form complementary paries. These are the following: Adenine pairs with Thynine (A - T), and Guanine pairs with Cytosine (G - C).

Question 5

DNA Structure (Order of pairings, and organism function)

Answer 5

• The rungs of the ladder could occur in any order as long as the Base-Pair rule is followed
• For example, a stretch of DNA could read AATGACCAT which would code for a different gene than a stretch that read, GGGCCATAG
• There are billions of bases (nucleotides) in cells which codes for all things an organism needs to function
• A complete DNA sequence in every cell is known as an organism

Question 6

DNA Replication

Answer 6

• Replication occurs during interphase, and it is when DNA makes a copy of itself
• The reason DNA has to replicate itself is because cells divide in order for organisms to reproduce, and inorder for those new cells to know how to be a cell, DNA has to replicate in order to give them instructions
• DNA replicates right before a cell divides
• DNA replication is SEMI-CONSERVATIVE meaning that each new DNA molecule consists half of the old strand in order to reduce the errors occuring while replicating

Question 7

DNA mutation

Answer 7

A change in the nucleotide sequence

Question 8

Pairing of Chromosomes

Answer 8

Chromosomes are paired:
* Number of chromosomes vary between each species
* Humans have 46 chromosomes with 23 from their mom, and 23 from their dad
* Sex chromosomes are X, and Y with females having XX, and males having XY
* Autosomes = All the 22 pairs of chromosomes except the sex chromosome

Question 9

Homologus Chromosomes

Answer 9

• Pairs of chromosomes that appear similar due to their length, centromere location, and banding pattern when stained
• They carry genes for traits at the same location (eg. such as eye colour)
• They can carry different forms of the same genes or alleles (one or two more alternating form of genes found in the same location of a centromere)
• These differences show as different traits