W14 Inheritance

Question 1

Define genetics and describe the mechanism of gene function.

Answer 1

DNA/ deoxyribonucleic acid is hereditary material. 2 strand polymore that stores info using a code.
adenine (A), cytosine (C), guanin (G) and thymine (T).
Acts as a template, making copies or to be decoded.

A gene also contains regulatory info hat dictates when and where a particular protein should be produced,

Protein synthesis:

• which proteins
• when to make them
• how much- where within the body

Question 2

Describe the human genome

Answer 2

The sequence of the entire human genome is 3 billion bases long. Helps in identification of disease causing genes

Question 3

Discuss the distribution of chromosomes to offspring; specifically, meiosis and the principle of independent assortment.

Answer 3

Meiosis: production of eggs and sperm, where only one of the pair of chromosomes is packaged into each sperm (haploid -1n). During fertilisation a full set of 23 pairs is reconstituted .

Question 4

Differentiate between the following sets of terms: dominant/recessive, genotype/phenotype, homozygous/heterozygous.

Answer 4

Dominant: an allele that masks or suppresses the expression of another allele. (larger T dominant)
Recessive: An allele whose expression is masked or suppressed by a dominant allele. (little t recessive)

Homozygous: Inheritance for two identical alleles for the one trait.
Heterozygous: Inheritance of two different alleles for the one trait

Genotype: describes the genetic makeup. (describing alleles)
Phenotype: the way ones genotype is expressed (describing characteristics)

Question 5

Explain how certain traits demonstrate the dominant-recessive mode of inheritance.

Answer 5

Each inherited trait is controlled by two sets of similar genes, one from each parent. In a punnet square.

Dominant: means that a single copy of the disease-associated mutation is enough to cause the disease.

Recessive: where two copies of the mutation are needed to cause the disease

Question 6

Explain how certain traits demonstrate multiple-allele inheritance.

Answer 6

Genes that exhibit more than two alternate alleles, ABO blood grouping is an example

Question 7

Explain the terms polygenic, incomplete dominance and codominance and give examples.

Answer 7

Both elleles influence the genetic trait or determine the characteristics of the genetic condition

Question 8

Explain how certain traits demonstrate sex-linked inheritance.

Answer 8

X genes are found on only the X chromosome. Only passed on to sons by their mothers. (Y chromosome must come from father).

Question 9

What is extrachromosomal (mitochondrial) inheritance?

Answer 9

,

Question 10

Briefly describe the basis for genetic diseases and give one example of a chromosomal disease.

Answer 10

Karyotype is a desciprtion of a persons chromosomes, Determining the sex chromosomes. OTher 22 pairs of chromosomes are called autosomal chromosomes, abnormalities can be detected.

Down syndrome is an example.

Question 11

How are genetic traits identified? Define and describe a pedigree, the Punnett square, and the karyotype.

Answer 11

,

Question 12

Predict the probability of inheriting certain genotypes & phenotypes using punnet squares.

Answer 12

,

Question 13

Discuss the distribution of chromosomes to offspring

Answer 13

Mitosis, this is where normal body cells divides, it is at this time that we can see the full complement of chromosomes.

23 pairs of chromosomes, mum and dad.

Question 14

What is Transcription?

Answer 14

Transcibed into an RNA molecule by the nucleus by RNA polymerase.

Transciption: strand of DNA template to build a molecule

Question 15

What is translation?

Answer 15

Translation: RNA molecule created in transcription process delivers info from DNA protein building machines

Question 16

Describe protein synthesis

Answer 16

Proteins are important structural components of cells and extracellular material. All enzymes are proteins, therefore metabolism is required.
Chromosomes → to genes each copy is referred to as an allele, performing the same function and in other cases performing different functions (eg skin colour, hair colour)

Question 17

Can you ellaborate phenotype TT Tt tt qualities with an example?

Answer 17

The phenotype red hair is determined by a single pair of recessive alleles.

Whereas the phenotype freckles is an example of a strict dominance and requires only one allele for the trait to be expressed

Question 18

Discuss the principle of independent assortment

Answer 18

1. Segregation: refers to the separation of the paired alleles (mitosis), resulting in number of possible chromosomes.
2. Independent assortment → segregation, random assortment of chromosomes from X + Y (mum and dad)
3. Random fertilisation: a single oocyte is fertilized by a single sperm in in a random manner
4. Recombination: homologous chromosomes can exchange info during meiosis
5. Environmental impact on gene expression: poor nutrition, influences genetic expression
6. Genomic imprinting: Same allele canhave different effects depending upon the source of parent

Question 19

Explain the term incomplete dominance

Answer 19

The dominant allele only partially masks the recessive allele. For example aberrant haemoglobin is the result of a partially recessive allele