Genetic T3

Question 1

What is sexual reproduction?

Answer 1

Sexual reproduction is where genetic information from 2 organisms ( a father and a mother) is combined to produce offspring which are genetically different to either parent

Question 2

What are gametes?

Answer 2

Gamete only contain half the number of chromosomes of normal cells - they are haploid. Normal cells are diploid

Question 3

What happens at fertilisation?

Answer 3

At fertilisation, a male gamete fuses with a female gamete to produce a fertilised egg, also known as a zygote. The zygote ends up with full chromosomes

Question 4

What is meiosis?

Answer 4

Meiosis is a type of cell division. It’s different to mitosis because it doesn’t produce identical cells, in humans, meiosis only happens in the reproductive organs

Question 5

How does meiosis work?

Answer 5

Before cells start to divide, it duplicates it’s DNA, one arm of each x-shaped chromosome is an exact copy of the other arm.in the first division, , the chromosomes line up, one chromosome in each pair came from the mother and one from the father. The pairs are then pulled apart and create 2 new cells, each cell has a mixture of chromosomes from the mother and father

Question 6

What are the advantages of asexual reproduction?

Answer 6

Asexual reproduction can produce lots of offspring very quickly, this can allow organisms to colonise an area very quickly
Only one parent is needed - this means organisms can reproduce whenever conditions are favourable without having to wait for a mate

Question 7

What are the disadvantages of asexual reproduction?

Answer 7

There is no genetic variation between offspring in the population. So if there is an environmental change or conditions become unfavourable, the whole population is affected

Question 8

What is the advantages of sexual reproduction?

Answer 8

Sexual reproduction creates genetic variation within the population, which mean different individuals have different characteristics. This can lead to natural selection and evolution as species become better suited to their enviroment

Question 9

What is the disadvantages of sexual reproduction?

Answer 9

Sexual reproduction takes more time and energy than asexual reproduction, so organisms produce less offspring in their lifetime, two parents are also needed, this could be a problem if individuals are isolated.

Question 10

What is DNA made of?

Answer 10

Polymers made up of lots of repeating units called nucleotides

Question 11

What is each nucleotide made of?

Answer 11

Each nucleotide consists of one sugar molecule, one phosphate molecule and one base

Question 12

How are nucleotides arranged in a DNA strand?

Answer 12

The sugar and phosphate molecules in the nucleotides form a backbone to the DNA strands. One of four different bases join to each sugar. The bases are A: adenine, T: thymine, C: cytosine and G: guanine

Question 13

What are chromosomes?

Answer 13

Chromosomes are long, coiled up molecules of DNA. They are found in the nucleus of Eukaryotic cells

Question 14

What are proteins made from?

Answer 14

Amino acids

Question 15

What are non- coding regions?

Answer 15

Many regions of DNA are non - coding, this means they don’t code for any amino acids

Question 16

What is a gene?

Answer 16

A section of DNA which codes for particular proteins, it’s the order of the bases in the gene that decides the order of amino acids in a protien

Question 17

What is a mutation?

Answer 17

A mutation is a rare, random change to an organism’s DNA base sequence that can be inherited. This could end up changing characteristics of the organism

Question 18

What are the 2 stages if protein making called?

Answer 18

Transcription and translation

Question 19

What happens in transcription?

Answer 19

Proteins are made in ribosomes in the cytoplasm, by sub cellular structures called ribosomes, DNA is found in the cell nucleus and cant move out of it because its too big. The cell needs to get the information from the DNA to the ribosome in the cytoplasm. This is done using a molecule called messenger RNA. Like DNA , RNA is a polymer of nucleotides, but its shorter and only a single strand. RNA polymerase is the enzyme involved in joining together RNA nucleotides to make RNA

Question 20

What happens in translation?

Answer 20

Amino acids are brought to the ribosome by a tRNA, the order which the amino acids are brought to the ribosome matches the order of base triplets in mRNA. Base triplets in mRNA are also known as codons. Part of the tRNA’s structure is called an anti codon - it is complementary to the codon for the amino acid. The pairing of the codon and the anticodon makes sure the that the amino acids are brought to the ribosome in the correct order

Question 21

What work did Mendel do to pea plants to develop the first ideas of genetics?

Answer 21

Mendel crossed two pea plants of different height, (one short, one long) the offspring were all long pea plants. He then bred two of these tall offspring together. He found that for every 3 tall pea plants made, there was 1 short pea plant

Question 22

What 3 important conclusions did Mendel come up with?

Answer 22

Characteristics in plants are determined by hereditary units
Hereditary units are passed on to offspring unchanged from both parents, one unit from each parent
Hereditary units can be dominant or reccesive

Question 23

What are dominant and recessive alleles?

Answer 23

Some alleles are dominant, and some are recessive, dominant alleles overrule recessive alleles, so of there is a Aa, the dominant characteristic will be present

Question 24

What is heterozygous and homozygous?

Answer 24

If an organism has 2 alleles for a particular gene that are the same, then it’s homozygous, if its two alleles are different, then it is hetrozygous

Question 25

What is a genotype?

Answer 25

Your genotype is the combination of alleles you have

Question 26

What is your phenotype?

Answer 26

You alleles determine what characteristics you have

Question 27

What pair of chromosomes determine what gender you are and how?

Answer 27

The 23rd pair, the last one. The pair is labeled XY or XX. Males have an XY chromosome. The Y gives them male characteristics and XX gives females their characteristics

Question 28

What gametes contain the X or Y chromosome?

Answer 28

The egg always has an X chromosome, but the sperm has an X or Y chromosome

Question 29

How is colour blindness caused?

Answer 29

It is caused by a faulty allele carried on the X allele

Question 30

How many alleles are there for blood type and how do they work?

Answer 30

Ia, Ib and Io. Ia and Ib are co dominant so if they are together than the blood type is just AB but the Io is recessive so it needs to be Io and Io to get the o blood type

Question 31

How is genetic variation caused in a organism?

Answer 31

Genetic variation within a species is caused by organisms having different alleles which can lead to differences in phenotype

Question 32

What was the human genome project?

Answer 32

Thousands of scientists from all over the world collaborated on the human genome project. The big idea was to find every single human gene. Over 13 years, all 20500 genes were found

Question 33

What are the medical applications for the human genome project?

Answer 33

Prediction and prevention of diseases,
Testing and treating inherited disorders
New and better medicines

Question 34

Name the gametes in humans

Answer 34

Sperm and egg