DNA genes and chromosomes

Question 1

Nuclear eukaryotic DNA is linear and associated with proteins. Explain the structure of eukaryotic DNA in detail including histones
- how and where is it wound .

Answer 1

-1- eukaryotic cells contain linear DNA that exists as chromosomes which are found in the nucleus
2- the DNA molecule is really long so it’s wound up to fit in the nucleus
3- the DNA molecule is wound around proteins called histones
4- the DNA is done coiled up very tightly to make a compact chromosome

Question 2

Describe DNA in mitochondria and chloroplasts

Answer 2

• Mitochondria and chloroplasts in eukaryotic cells have their own DNA
• This is similar to prokaryotic DNA because it is circular and shorter than DNA molecules in the nucleus
• It is not associated with histone proteins

Question 3

Describe the structure of DNA molecules in prokaryotes

Answer 3

• dna is shorter and circular
• dna isn’t wound around his stones
• It condenses to fit in the cell by supercoiling

Question 4

What does a sequence of three bases in a gene code for?

Answer 4

A triplet

Question 5

What is a gene?

Answer 5

A sequence of DNA bases that codes for either a polypeptide or functional RNA 

Question 6

Describe how genes can code for functional RNA

Answer 6

• to make a polypeptide DNA‘s first copied into mRNA, which is the first stage of protein synthesis
• Genes that don’t code for a polypeptide code for functional RNA instead functional RNA is RNA molecules other than mRNA which perform special tasks during protein synthesis

Question 7

What is an Intron?

Answer 7

Sections of polypeptides that don’t code for amino acids
- There are several in terms within a gene

Question 8

What are Exxon’s?

Answer 8

The parts of the gene do code for amino acids

Question 9

What are removed during protein synthesis?

Answer 9

Intron so that they don’t affect amino acid order

Question 10

What are non-coding repeats?

Answer 10

Regions of multiple repeats outside of jeans which are DNA sequences that repeat over and over and don’t code for amino acids

Question 11

How many pairs of chromosomes do humans have?

Answer 11

23

Question 12

What are pairs of matching chromosomes called?

Answer 12

Homologous pair

Question 13

Characteristics of homologous pairs

Answer 13

• Chromosomes are the same size and have the same genes
• Can’t have different alleles

Question 14

where will alleles coding for the same characteristic be found

Answer 14

same fixed position/ locus on each chromosome in a homologous pair