Inheritance

Question 1

Define the term inheritance

Answer 1

The transmission of genetic information from generation to generation/parents to offspring

Question 2

What is a chromosome?

Answer 2

A thread-like structure of DNA that carries genetic information in the form of genes

Question 3

What is a gene?

Answer 3

A length of a DNA that codes for a specific protein that plays an important role in our cell activity

Question 4

What is an allele?

Answer 4

One version of a gene

Question 5

What is a diploid nucleus?

Answer 5

Nuclei containing 2 sets of chromosomes (46 chromosomes)

Question 6

What is a haploid nucleus?

Answer 6

Nuclei containing one set of chromosomes (23 chromosomes). These are egg and sperm cells which fuse during fertilisation.

Question 7

What are the two main processes of Protein Synthesis?

Answer 7

transcription and translocation

Question 8

How is a protein made?

Answer 8

• Specific sequences determines
• Specific sequence of amino acids used to make a
• Specific protein

Question 9

Why does the specific sequence of genes need to be transcribed? (Transcription)

Answer 9

-The DNA is located in the nucleus
- The specific sequence of genes needs to be read by ribosomes which are outside the nucleus.
- However, the DNA is too big and can’t leave the nucleus
- So mRNA (messenger) makes a copy that is small enough to leave the nucleus.

Question 10

How is the mRNA different from a DNA?

Answer 10

• It is much shorter than the DNA (able to leave the nucleus)
• It is only a single strand
• Instead of T (Thymine) it contains U (Uracil)

Question 11

Where are the mRNA molecules made?

Answer 11

They are made in the nucleus and move to the cytoplasm

Question 12

Describe the process of transcription (protein synthesis)

Answer 12

• The mRNA will be complimentary to the DNA
• It moves along the DNA and copies the gene
• An enzyme called the RNA polymerase binds with the DNA where the gene starts
• The DNA strand separates just ahead of the RNA polymerase and closes just behind it - only exposing 4 genes at a time.
• Once the mRNA has copied the desired gene the RNA polymerase detaches from it and the DNA strands close back up
  The mRNA is free to leave the nucleus and head to the ribosome.

Question 13

What are the letter combinations for the mRNA strand?

Answer 13

C - G
G - C
T - A
A - U

Question 14

Describe the process of translation (protein synthesis)

Answer 14

• The mRNA will pass through the ribosome and it will bind together
• The ribosome will read the first three genes and will attract the tRNA (transfer RNA)
• The tRNA will bring the amino acid that is complementary to the one on the mRNA
• The tRNA will leave the amino acid behind
• In the end, the amino acid will detach itself from the ribosome
• The final sequence of amino acids will fold up to become a protein
• Different sequences of amino acids give different protein

Question 15

Name the 3 different types of proteins

Answer 15

• Enzymes
• Antibodies
• Receptors for neurotransmitters

Question 16

Describe mitosis

Answer 16

Nuclear division, giving rise to/increasing identical cells

Question 17

What is the role of mitosis?

Answer 17

• Growth
• Repair of damaged tissues
• Replacement of cells
• Sexual reproduction

Question 18

What happens during mitosis?

Answer 18

• When cells divide, their chromosomes divide beforehand
• This ensures that each new cell, when split into two, will have two sets of chromosomes - maintaining the chromosome number

Question 19

What is a stem cell?

Answer 19

• It is an unspecialised cell
• Divide by mitosis to produce daughter cells that can become specialised cells

Question 20

What is meiosis?

Answer 20

It is the reduction division where the number of chromosomes is halved from diploid to haploid
- Results in genetically different cells