Chapter Three: Flashcards
What are the three advantages of Asexual Reproduction?
+Rapid Populating
+No mates required
+Emergency option
What are the three disadvantages of Asexual Reproduction?
- No diversity
- Prone to extinction
- Cannot adapt
Why is rapid populating an advantage of asexual reproduction?
Asexual reproduction gives the ability to produce large quantities of offspring
Why is not having a mate an advantage of asexual reproduction?
Finding a mate can be difficult for organisms in desolate environments
Why is asexual reproduction a good emergency option?
In dire situations, plants and organisms can keep themselves alive and produce others to help them.
Why does asexual reproduction produce offspring with no diversity?
Traits are only passed on from one parent, so there is no genetic mixing meaning all offspring produced are identical.
Why are offspring of asexual reproduction prone to extinction?
Same traits mean same weaknesses. Predators that have evolved to kill a single organism can wipe out an entire population.
Why can the offspring of asexual reproduction not adapt?
An organism has established reactions to certain things which are passed down in asexual reproduction, making it almost impossible for them to adapt to any environment changes.
What is the purpose of sexual reproduction?
To produce offspring that resemble the parents, but are not identical.
What are the sex cells called in organisms?
Gametes
Name the advantages of sexual reproduction:(2)
More variation - more chance of survival
Bad genes can become extinct through meiosis and natural selection
Name the disadvantages of sexual reproduction:(4)
Requires two parents
Takes time and energy
Favorable genes can also become extinct through meiosis
Produces less offspring than asexual reproduction
What is Meiosis?
A type of cell division that produces gametes
How many chromosomes does a human body cell contain?
46 (23 pairs)
How many chromosomes does a gamete contain?
23
How does Meiosis differ to Mitosis?
They produce four daughter cells
What does Meiosis produce?
Four genetically haploid daughter cells
What is the Genome?
The haploid set of chromosomes
What is formed at fertilization?
A Zygote
What does a zygote contain?
23 pairs of chromosomes - 23 single chromosomes from each parent
What do chromosomes contain?
Genes
What are Genes?
A distinct sequence of nucleotides forming part of a chromosome
What does DNA stand for?
Deoxyribose Nucleic Acid
What is DNA?
The complex chemical that carries genetic information
What are chromosomes?
A thread-like structure of nucleic acids and proteins. Carries genetic information in the form of genes.
What are the function of the bases in DNA?
To carry different codes needed for different amino acids
What is the code for an amino acid made of?
Three bases in a particular order
What are the four different bases of DNA?
Thymine, T
Adenine, A
Guanine, G
Cytosine, C
What does Thymine pair with?
Adenine
What does Guanine pair with?
Cytosine
What bonds hold the bases of DNA together?
Hydrogen Bonds
What bases form three hydrogen bonds?
Guanine and Cytosine
What bases form two hydrogen bonds?
Adenine and Thymine
What are Proteins made up of?
Large numbers of amino acid molecules
What is a Mutation?
A change that occurs in a gene
What causes a Mutation?
They can be random or caused by radiation or chemicals.`
What do Mutations cause? (Terms of genetic code)
Alteration to the base pair sequence
What’s the difference between DNA mutations in normal body cells and sex cells?
If changes occur in normal body cells, the changes are lost when we die. If changes occur in sex cells, there is a possibility they will be passed on to the next generation.
How is a new species produced?
Through the combined effect of mutations, environmental changes and natural selection
What is transcription?
The copying of DNA in the process of creating a protein.
Where does transcription occur?
In the cell nucleus
What is the first stage of Transcription?
The DNA in a gene unzips so both strands are separate
What is the second stage of Transcription?
Complementary bases attach to the strand being copied.
What is the third stage of Transcription?
Thymine is not present so a different base (U) joins with Adenine
What is the fourth stage of Transcription?
Messenger RNA is formed
What is the difference between DNA and mRNA? (In terms of exiting/entering the nucleus)
mRNA is small enough to leave the nucleus and travel to the ribosomes in the cytoplasm.
What is translation?
The process of mRNA being interpreted and new proteins forming
Where does translation take place?
In the Ribosomes
What is the first step of Translation?
The mRNA attaches to a ribosome which ‘reads’ the mRNA
What is the second step of Translation?
The ribosome decodes the mRNA in groups of three (base triplets or codons) which are complementary in transfer RNA
What is the third step of Translation?
The tRNA collects its specific amino acids and returns to the mRNA
What is the fourth step of Translation?
The amino acids are lined up in order of the instructions of the mRNA
What is the fifth step of Translation?
Bonds form between the amino acids and a polypeptide chain is formed
What is the sixth step of Translation?
The polypeptide chain folds and becomes a specific shape forming a protein
What is an allele?
each of two or more alternative forms of a gene that arise by mutation
What does dominant mean in the terms of genetics?
an allele or a gene that is expressed in an organism’s phenotype, masking the effect of the recessive allele or gene when present
What does recessive mean in the terms of genetics?
an allele or gene in which the effect is masked by the effects of a dominant gene or allele
What does Homozygous mean?
When an individual has two of the same allele
What does Heterozygous mean?
When an individual has two alleles that are different
What is a genotype?
the genetic constitution of an individual organism
What is a phenotype?
A set of observable characteristics of an individual
What is cystic fibrosis caused by? (In the terms of alleles)
Recessive Allele
What does Cystic Fibrosis cause?
The individual to produce abnormally thick and sticky mucus in their lungs and airways
If a person has one copy of the allele causing CF but one not carrying CF, what are they referred to as?
A carrier
What is an example of multiple alleles for one gene?
The ABO blood group
What is codominance?
When two or more alleles are expressed in the same phenotype
Which is more domination? I^A or I^B?
Neither, none are dominant over each other
True or False? Both I^A and I^B are dominant over I^O.
True
If a person has the genotype I^A I^O, what phenotype are they?
A
What sex chromosomes code for a male?
XY
Why does the sperm determine the sex of the fetus?
The Sperm carries the alternating sex chromosome, the ovum always contains the X chromosome but the sperm can contain either the X or Y.
What are the effects of Haemophilia?
People with it have a problem forming blood clots
What causes Haemophilia?
A recessive gene on the X chromosome
What environmental factors can affect our phenotype?(5)
- climate
- diet
- physical accidents
- culture
- lifestyle
