3.28-3.39 inheritance part 2

Question 1

What is Mitosis?

Answer 1

nuclear division giving rise to genetically identical cells

Question 2

Why does mitosis happen?

Answer 2

Mitosis is used for growth repair of damaged tissues, replacement of cells and asexual reproduction

Question 3

What is a diploid?

Answer 3

2 complete pairs of chromosomes

Question 4

What is duplication?

Answer 4

When cells divide their chromosomes double beforehand this ensures that when the cell splits into two each new cell still has two copies of each chromosome (diploid)

Question 5

Explain the process of Mitosis

Answer 5

Just before mitosis each chromosome in the nucleus copies itself exactly to form x shaped chromosome
The Chromosomes then line up along the centre of the cell where the cell fibres pull them apart
The cell then divides into two each new cell has copy of each pf the chromosome

Question 6

Why is Mitosis important?

Answer 6

All cells in the body (excluding gametes) are produced by mitosis of the zygote
Mitosis is important for replacing cells and for allowing growth and production of new cells.

Question 7

What key processes happen during mitosis?

Answer 7

Growth- mitosis produces new cells
Repair- to replace damaged or dead cells
Asexual reproduction- mitosis produces offspring that are genetically identical to the parents

Question 8

What is Meiosis?

Answer 8

Meiosis is a type of nuclear division that gives rise to cells that are genetically different

Question 9

What is Meiosis used to do?

Answer 9

Meiosis is used to produce the gametes the number of Chromosomes must be halved when the gametes are formed, otherwise there would be double the number of Chromosomes after fertilisation.

Question 10

Explain the process of meiosis

Answer 10

Each Chromosome makes identical copies of itself forming x shaped chromosomes.
First division- chromosomes pair along the centre of the cell, recombination occours and then cell fibres will pull the pairs apart each new cell has one of each recombination chromosomes pair.
Second division- chromosome will line up in the centre of the cell the cell fibres pull them apart again.
a total of four haploid daughter cells are produced

Question 11

What is the importance of meiosis?

Answer 11

Production of gametes
increased genetic variation of offspring
Meiosis’s produces variations forming new combination of maternal and paternal chromosomes every time a gamete is made meaning when they fuse randomly at fertilisation each offspring is different from the others

Question 12

What are the differences between Mitosis and Meiosis

Answer 12

mitosis - two daughter cells produced meiosis - four daughter cells produced
mitosis - daughter cells are diploid meiosis - daughter cells are haploid
Mitosis- daughter cells are genetically identical to each other and the parents cell meiosis- daughter cells are genetically different from each other and parent cells
Mitosis- one cell division occours meiosis- two cell divisions occour

Question 13

What controls Phenotypic variation?

Answer 13

It can be genetic controlled entirely by genes
it can be environments caused entirely by the environment which the organism lives.

Question 14

Give an example of genetic variation within a human

Answer 14

Meiosis creates genetic variation between the gametes produced in an individual meaning each gamete carries different alleles
During fertilization any male gamete can fuse with any female gamete to form a zygote
random fusion of gametes at fertilization causes genetic variation between zygotes having a unique combination of alleles which will then grow into adults

Question 15

Give examples of genetic variation in characteristics of a human?

Answer 15

Blood group
eye colour
gender
ability to roll tongue

Question 16

What is environmental variation?

Answer 16

Characteristics of all species can be affected by environmental factors like climate diet accidents culture and life style.
Examples are
An accident may lead to scarring on the body
Eating too much and not having an active lifestyle cause weight gain
Being raised in a country will cause you to speak a language with a certain accent
A plant in the shade of a tree will row taller to reach more sunlight

Question 17

Give examples of Genetic and environmental causes?

Answer 17

Tall parents will pass genes to their children for height
Their children will have the genetic potential to be tall
but if their diet is poor they might no grow as tall
Therefore their environment also has impact on height

Question 18

What is a diploid cell?

Answer 18

A diploid cell is a cell that contain two complete sets of Chromosomes they contain the DNA necessary for protein synthesis and cell function nearly all cells in the body are diploid with 23 pairs pairs (46) chromosomes in their nucleus

Question 19

What are haploid cells?

Answer 19

A Haploid cell contains one complete set of chromosomes, they have half the number of chromosomes compared to diploid cells
Humans have haploid cells that contain 23 chromosomes in their nucleus
These haploid cells are called gametes and they are involved in sexual reproduction for humans they are the female egg and the male sperm

Question 20

What is Variation?

Answer 20

Variation is defined as differences between individuals of the same species

Question 21

What are the two types of Variations?

Answer 21

Continuous variation- when there is a very small degree of difference for a particular characteristic between individuals and they are arranged in order and can usally be measured on a scale.

Discontinuous Variation: is when there is distinct difference for a characteristics

Question 22

Wat are mutations?

Answer 22

Mutations are rare and random changes that occour in the sequence of DNA bases in a gene or a chromosome mutations occour continuously.
As the DNA base sequence determines the sequence of amino acids that make up a protein mutations in a gene can sometimes lead to a change in the protein that the genes code for

Question 23

What do mutations do a protein?

Answer 23

Most mutations do not alter the protein or only alter it slightly so that its appearance or functions is not changed
A small number mutations code for a significantly altered protein with a different shape. Different mRNA is formed during transcription.

Question 24

What can mutations lead to?

Answer 24

On rare occasions lead to the development of new alleles and so new phenotypes.
Occasionally the new allele gives the individual a survival advantage over member of a species

Question 24

What is sickle cell anaemia?

Answer 24

Sickle cell anaemia was the first genetic disease to be a gene mutation.
A gene mutation changes the base sequence of DNA
The mutation changes the molecule haemoglobin causing the red blood cells to become stiff sickle shaped when they release oxygen to the body tissue. The sickled cell tends to get stuck in narrow blood vessels , blocking the flow of blood

Question 24

What harmful changes can mutations cause?

Answer 24

Mutations can also lead to harmful changes that can have effects on the body for example, sickle cell anaemia

Question 25

What are the general causes of mutations?

Answer 25

Mutations can be increased be exposure to Gamma rays, x- rays and ultraviolet rays all types of ionising radiation which can damage bonds and cause changes in base sequences
Certain types of chemicals- for example chemicals such as tar in tobacco

Increased rates of mutations can cause cells to become cancerous which is why these can cause cancers

Question 25

What conditions can sickle cell anaemia cause

Answer 25

Stokes, blindness damage to the lungs kidneys or hearts can cause the person to be hospitalised for blood transfusions and at risk of life threatening complications.

Question 26

What is an insertion?

Answer 26

A new base is randomly inserted into the DNA sequence, an intersection mutation changes the amino acid that would have been coded for by the group of three bases, which the mutation has occoured

Question 27

How many bases is required to code an amino acid?

Answer 27

Every group of three bases in a DNA sequence codes for an amino acid

Question 28

What are Deletions?

Answer 28

A base is randomly deleted or missed out from the DNA sequence,
a deletion mutation changes the amino acid that would of been coded for by the group of 3 bases
a deletion mutation has knock on effects by changing the groups of three bases further on in the DNA sequence

Question 29

What is Substitutions?

Answer 29

A base in the DNA sequence is randomly swapped for a different base
Unlike an insertion or deletion mutation a substitution mutation only changes the amino acid for the group of the three bases in which the mutation occours doesn’t have any knock on effects

Question 30

What are antibiotics?

Answer 30

Chemical substances made by fungi or bacteria that affect the working of bacterial cells, by disrupting their structure or function preventing them from reproduction
Antibiotics are effective against bacteria not viruses though

Question 31

Where do antibiotics target?

Answer 31

processes and structures that are specific to bacterial (prokaryotic) cells; as such they do not generally harm animal cells

Question 32

What is Evolution?

Answer 32

The change in the frequency of a phenotype in a population of many generation?

Question 33

What is the theory on evolution?

Answer 33

Individuals in a species show a wide range of variation caused by differences in genes
Individuals with characteristics most suited to the environment have a higher chance of survival and more chances to reproduce
Therefore these characteristics are passed to their offspring at a higher rate than those with characteristics less suited to survival
Over many generations, these beneficial characteristics become more common in the population and the species changes (the species evolves)

Question 34

What Mutations have Bacteria developed because of Overused antibiotics

Answer 34

Bacteria, like all organisms, have random mutations in their DNA
One of these mutations may give them resistance to an antibiotic
If an organism is infected with bacteria and some of them have resistance, they are likely to survive treatment with antibiotics

Question 35

How can resistant bacteria be prevented?

Answer 35

To reduce the number of bacteria that are becoming resistant to antibiotics:
Doctors need to avoid the overuse of antibiotics, prescribing them only when needed – they may test the bacteria first to make sure that they prescribe the correct antibiotic
Antibiotics shouldn’t be used in non-serious infections that the immune system will ‘clear up’
Antibiotics shouldn’t be used for viral infections
Patients need to finish the whole course of antibiotics so that all the bacteria are killed and none are left to mutate to resistant strains
Antibiotics use should be reduced in industries such as agriculture

Question 36

How can general people reduce the spread of resistant bacteria?

Answer 36

Good hygiene practices such as handwashing and the use of hand sanitisers have reduced the rates of resistant strains of bacteria, such as MRSA, in hospitals
The isolation of infected patients to prevent the spread of resistant strains, in particular in surgical wards where MRSA can infect surgical wounds

Question 37

Why can’t Antibiotics affect viruses?

Answer 37

Viruses cannot be treated with antibiotics
This is because antibiotics work by disrupting cell functions such as respiration, or breaking down the structure of the cell in some way
However, viruses do not carry out any cell functions and do not have cell walls, cell membranes or any cell organelles as viruses infect and utilise the machinery of animal cells to reproduce, which are not affected by antibiotics.
Therefore the action of antibiotics do not affect them

Question 38

What is inversion?

Answer 38

A sequence of bases on a triple code is reversed. Only one triplet is altered only one codon on the mRNA will be different resulting in a maximum impact of one different amino acid in the sequence coded for. It may by chance still code for the same amino acid.

Question 39

What is mutagen?

Answer 39

Something that increases the likelihood of a mutation occurring

Ionising radiation like gamma rays, x rays and ultra Violet rays.