Unit 4 Topic 1 Bio

Question 1

qQWhat is DNA made out of?

Answer 1

Nucleotides.

Question 2

What are Nucleotides?

Answer 2

• A phosphate group.
• A sugar group.
• A nitrogen-containing base.

Question 3

What are DNA strands? And how does it work?

Answer 3

1. When nucleotides join to form a polynucleotide chain, or strand.
2. The sugar and phosphate groups join by covalent bonding to form the backbone of the DNA molecule.

Question 4

What are the 5 different nitrogen bases?

Answer 4

• Adenine (A).
• Guanine (G).
• Cytosine (C).
• Thymine (T).
• Uracil (U).

Question 5

How is DNA packaged?

Answer 5

When DNA condenses during cell division, DNA is packaged tightly into chromosomes which are found in the nucleus. This is done by wrapping around histone proteins which continually wrap and coil to create a supercoil.

Question 6

Where is DNA found in Prokaryotic and Eukaryotic cells.

Answer 6

Prokaryotes: DNA is found in the cytoplasm of prokaryotes as unbound circular DNA.
Eukaryotes: Most of the DNA is in the nucleus in chromosomes. Some DNA is also found in the mitochondria and chloroplast as unbound circular DNA.

Question 7

What are Sister Chromatids?

Answer 7

When DNA is replicated, one chromatid is copied to create two chromatids. These contain the same DNA.

Question 8

What are Homologous Chromosomes?

Answer 8

Two different chromosomes from each parent that encode the same information.

Question 9

Identify the first stage of Meiosis 1 and define it.

Answer 9

Prophase 1 -> Homologous chromosomes condense and come together to form a tetrad. Crossing over and recombination occurs where multiple segments of non-sister chromatids overlap, break and reattach to the other chromatid, creating variation.

Question 10

What is Helicase?

Answer 10

An enzyme that unzips the two strands to create a replication fork

Question 11

What is DNA polymerase?

Answer 11

An enzyme that adds nucleotides to the template strands to build two complementary strands.

Question 12

Recall the stages of mitosis.

Answer 12

Interphase, Prophase, Metaphase, Anaphase, Telophase.

Question 13

Describe the phases of Meiosis.

Answer 13

Meiosis:

Question 14

Define Spermatogenesis.

Answer 14

The production of sperm in the testes.
Approx 400 million sperm daily.

Question 15

Define Oogenesis.

Answer 15

When only one viable haploid cell over a series of events is produced through Meiosis.

Question 16

Define Independent Assortment.

Answer 16

Recombined chromosomes are aligned at the equator.

Question 17

Define Random Fertilisation.

Answer 17

If two people reproduce, the random chance of any one sperm and egg coming together is estimated to have some 70 trillion possible combinations.

Question 18

Define a Gene

Answer 18

A sequence of nucleotides that encodes the synthesis of a gene product, either RNA or protein.

Question 19

Define a Genome

Answer 19

The complete set of genetic material (DNA) present in an organism, measured in the number of base pairs contained.

Question 20

What is contained within a genes structure

Answer 20

Start Codons
Stop Codons
Promoter Regions
Coding Regions -> Exons
Non-Coding Regions -> Introns

Question 21

Define the purpose of Exons

Answer 21

Exons are used to make proteins or RNA

Question 22

Define Transcription

Answer 22

The synthesis of mRNA from DNA.

Question 23

Identify the steps of Transcription

Answer 23

Initiation, Elongation, Termination.

Question 24

Define Initiation

Answer 24

RNA polymerase binds to the promoter region of the gene and breaks the hydrogen bonds between strands, causing them to separate and create a ‘transcription bubble’.

Question 25

Define Elongation

Answer 25

The RNA polymerase moves along the gene, nucleotides are added by complementary base pairing. The DNA strands behind the transcription bubble recoil back together as the mRNA is forming.

Question 26

Define Termination

Answer 26

Transcription ends when RNA polymerase reaches the termination site of the gene. This region contains a stop codon which causes RNA polymerase to detach, releasing mRNA.

Question 27

Define Translation

Answer 27

The information in mRNA is read and used to build a chain of amino acid.

Question 28

Identify the key component of translation. And define.

Answer 28

Ribosomes. They contain two subunits that come together around the mRNA strand. Then tRNA is used to add the specific amino acid to the chain.

Question 29

Define Gene Expression

Answer 29

Produces a functional gene product, either protein or functional RNA.

Question 30

Define Transcription Factors

Answer 30

Proteins that bind to specific sequences to control gene expression.

Question 31

Identify the causes of mutation

Answer 31

DNA replication, Cell division, Damages by mutagens.

Question 32

Identify the 2 mutations that can lead to errors in DNA replication.

Answer 32

Point Mutation, Frameshift mutation.

Question 33

Define a Point Mutation

Answer 33

Involves a change in one base in the sequence.

Question 34

Define a Frameshift mutation

Answer 34

An insertion or deletion of one or more bases, shifting several codons.

Question 35

Define Autosomal Dominant

Answer 35

A trait that is often seen in all generations.Must have one parent with the trait.

Question 36

Define Autosomal Recessive

Answer 36

Neither parent has a phenotype but one or more offspring do.

Question 37

Define X-Linked Dominant

Answer 37

Males who are affected will always have daughters with the trait and sons without (rare).

Question 38

Define X-Linked Recessive

Answer 38

Females who are affected will have sons with the trait.

Question 39

Define Y-Linked Inheritance

Answer 39

Only males can be affected and pass down to all sons.

Question 40

What is a Polymerase Chain Reaction or PCR?

Answer 40

A single or few copies of DNA are replicated into millions or billions of copies.