Biology: Introduction to Genetics and Evolution

Flashcards reviewing key concepts from the Biology half-yearly exam study guide, covering genetics, cell structure, DNA, heredity, and evolution.

What is genetics?

The study of DNA, genes, and inherited characteristics that makes up variations in a population.

Identify examples of inherited characteristics.

Eye colour, nose shape, hair type, body structure, etc.

Define variation and outline its importance.

The difference in the population that allows people to survive and adapt in changing environments.

Describe examples that show the effect of the environment on appearance.

Sun exposure, lifestyles, surgery, and diets.

Identify the structures within an animal cell.

Cytoplasm, nucleus, and cell membrane.

Outline the function of various structures within an animal cell.

Cell membrane: Controls what enters and exits the cell. Cytoplasm: Chemical reactions take place. Nucleus: Controls the cell, and the DNA is stored here.

What is the function of DNA?

Stores all coded information, which determines what you look like

Describe the structure of Chromosomes.

A ladder-like structure, located in the nucleus, is composed of DNA and proteins.

What is a gene?

A gene is a recipe or instruction to create a protein.

What are Nucleotides?

The basic building blocks of DNA containing sugars, phosphate and bases. (A & T always go together, and G & C always go together)

What was Mendel's contribution to our understanding of the structure of DNA?

He discovered how the characteristics of parents are passed down to their children by studying pea plants.

What was Miescher's contribution to our understanding of the structure of DNA?

He discovered there were nucleic acids which were inside the cell.

What was Kossel's contribution to our understanding of the structure of DNA?

He discovered the composition of nucleic acids, which were comprised of sugar, phosphates and bases.

What was Chargaff's contribution to our understanding of the structure of DNA?

He discovered and analysed the DNA of different species and observed that A will always go with T, and the same with G and C.

What was Franklins's contribution to our understanding of the structure of DNA?

She discovered the shape of the DNA by using X-rays as well as the 2 strands of sugar and phosphate.

What was Watson & Crick's contribution to our understanding of the structure of DNA?

Both discovered the structure of DNA.

Why is DNA Replication required?

Ensures that all new daughter cells receive an identical copy of the parent cells.

Describe the steps of DNA replication.

1. The DNA unwinds from the double helix shape. Then enzymes separate it like a zipper. 2. The original strand becomes a template for free nucleotides to attach their corresponding partner, A only goes with T and G with C. 3. The results are two identical strands of DNA

Outline the advantage of DNA replicating exactly.

It allows parents' favourable characteristics to be passed on to offspring.

Where does Mitosis occur?

In the division of cells, creating 2 new daughter cells.

What is the purpose of Mitosis?

To create new cells for growth, repair and replacement within an organism.

Describe the cells produced by Mitosis.

Body cells like skin, muscles, nerves, and bone cells.

Outline the process of Mitosis.

1. 2 pairs of chromosomes are visible 2. Chromosomes are doubled, now there are 92 chromosomes, but attached at the centromere 3. Chromosomes line up in the middle of the cell 4. Fibres will split the chromosomes and pull them to each end of the cell 5. Two membranes form to create 2 new daughter cells with 46 chromosomes in each.

Where does Meiosis occur?

In the sex cells.

What is the purpose of Meiosis?

To create new sex cells.

Describe the cells produced by Meiosis.

Sex cells (gametes) required for reproduction.

Outline the process of Meiosis.

1. Chromosomes find their partner 2. Then they line up in the middle of the cell 3. They are separated from their partner 4. The cell splits and divides into 2 5. Each chromosome in both cell lines up in the middle of the cell 6. The chromosomes are attached by fibres 7. Then the cell splits into 4

Compare the processes of Mitosis and Meiosis.

Mitosis is the process of making new body cells for the growth and repair of cells, and occurs in the body cells. Meiosis is the process of making new sex cells for reproduction, and occurs in the sex cells of males' testes and females' ovaries.

Describe the experiments carried out by Mendel.

Mendel started with purebred plants with different characteristics (one tall and one short). They were bred together and had offspring. He called the offspring F1 generation. He then cross-bred the plants from the F1 generation and recorded their appearance, calling the next generation F2.

Describe what Mendel discovered about inheritance.

Concepts that the dominant trait and recessive traits are passed down from parent to offspring.

Define Genotype.

The genetic make-up or content of an organism.

Define Phenotype.

The appearance of an organism is a result of its genetic content.

Define Allele.

Any 2 or more variants of a gene.

Define Dominant.

The trait that can hide or mask another gene. Only one gene needs to be present for the trait to be shown.

Define Recessive.

A trait that is hidden or masked by another trait. 2 genes need to be present for the trait to be shown.

Define Pure-breed (Homozygous).

When the 2 genes are the same

Define Hybrid (Heterozygous).

When the 2 genes are different.

Determine an individual's Genotype as either Homozygous or Heterozygous.

If it is homozygous dominant, it will be two capital letters. If it is homozygous recessive, it will be two lower-case letters. If it is heterozygous, it is one capital letter and one lowercase.

Outline the steps to use Punnett squares.

1. Designate characters to represent the allele, eg. Capital letter for dominant trait and lowercase letter for recessive trait. 2. Write down the genotypes of the parents. Father goes on top, and mother goes on the side. 3. Write down the genotypes of the parental gametes. 4. Use the Punnett square to work out the potential gamete combinations 5. Write down the genotype and phenotype ratios for the potential offspring.

Identify the chromosome combination for males and females.

Males: XY and Females: XX

Describe what an X-linked disorder is.

A genetic condition that is caused by a mutation on the X chromosome. More commonly in men, females are carriers of this mutation.

Know the symbols and guidelines used in Pedigrees.

Squares: Men, Circles: Women, Triangle: twins, horizontal line- marriage, coloured in means affected males and females.

Determine whether a characteristic is dominant or recessive based on a pedigree.

The characteristics are dominant if 2 affected parents have an unaffected child. The characteristics are recessive if 2 unaffected parents have an affected child.

Define mutation.

Mutations are a change in the genetic make-up of an organism.

Outline how and when mutations occur.

Mutations occur due to errors in DNA replication and when mutagens occur. It can occur at any point of a cells life.

Define and give examples of mutagens.

A mutagen is any chemical, biological or physical agent which causes a change in the genetic information of a living organism. For example uv light, X-rays, viruses, chemicals found in cigarete smoke, benzeneformlin found in pesticides.

Outline the difference between gene and chromosomal mutations.

A gene mutation is a single gene which is a nucleotide change which will affect the expression of only that gene. A chromosomal mutation occurs when a person has too many chromosomes or when a piece of one chromosome is deleted or attached tp another.

Describe the positive and negative effects of mutations (including examples).

The positive effects of mutation is that it may allow for an organism to increase its chance of survival by adapting and reproduction. The negative effects of mutation can led to genetic disorders or other health conditions.

Define Adaptation.

An adaptation is any feature or characteristic (which may have originated from a genetic mutation) which gives an organism an advantage and enables the organism to survive and reproduce in its environment.

Define Behavioural adaptations.

Actions that help an organism to survive and reproduce

Define Physiological adaptations:

Body processes that help an organism to survive and reproduce.

Define Structural adaptations:

Body features (body parts) that help an organism to survive and reproduce.

Describe plant and animal examples of adaptations (determine whether it is a structural, physiological or behavioural adaptation) and outline how it assists the organism to survive.

Camels have thick fur for shade, camouflaged, flat feet that help they walk on sand, long eyelashes that protect their eyes from sand, are able to tolerate high body temperatures, can drink gallons of water in one load, and lose very little water through sweating and urination.

Define Evolution.

The process by which populations can change genetically overtime.

Describe what natural selection is.

A process by which organisms with the favourable trait will be able to survive in a certain environment leading to the increase of the organism over time with reproduction. Those with the less favourable traits will often die.

Describe the steps of how Evolution could occur by the process of Natural Selection.

1. There needs to be variation in the population 2. Then there is a challenge. 3. The organism with the favourable trait will survive and reproduce. 4. The organism with the less favourable trait will die off. 5. Then over generations the population will now be filled with the organisms which have the favourable traits to survive in that environment.

Describe how evolution could occur by the process of Geographical Isolation.

All the organisms live on the same land mass in the same environment, however there is a geographical barrier like mountain, land movement, a river and these geographical barriers spilt the population of the organisms and they then adapt to their environment.

Define divergent evolution.

They start of similar but overtime they become more different, geographical barriers are an example of this. Start off with one (ancestor) and eventually spreads and becomes many. Divergent have a common ancestors.

Define convergent evolution.

They start of different but overtime they become more and more similar. This is due to sharing a similar environments. Very different animals that look similar they have the same characteristics and structure because they live in the same environment.

Describe examples of divergent and convergent evolution.

Rattits (flightless birds) is an example of divergent evolution. And sharks and dolphins is an example of convergent evolution.

Outline the theories of evolution proposed by Lamarck.

He believed that if organisms used a characteristic they kept it, if they didn’t use it they left it.

Outline the theories of evolution proposed by Darwin.

Darwin proposed natural selection that organisms can change when natural selection comes about. He went around on a boat around the world for 5 years and collected data. Each species has not always been the way we see them today and that all species change throughout generations.

Describe examples that illustrate the theories of evolution proposed by Darwin.

darwin proposed that there were many different types of giraffe one with a short neck and one with a long neck. And the giraffes with the favourable traits (having long necks) would be able to eat the food from the trees and survive and reproduce.

Describe the evidence used to support Darwin’s theory of evolution

Fossils Transitional form (archeopteryx) Anatomical similarities Geographical similarities Comparative embryology Biochemical similarities

Paleontology (Fossils)

The study of fossils, including their identification and interpretation

Comparative anatomy (Pentadactyl limb)

The study of the structure of specific organs and limbs of different organisms

Comparative embryology

The study of the development of the embryo in different organisms

Biogeographical evidence (Ratites)

The ability to sequence DNA to indicate the degree of relatedness between organisms

Biochemistry

The similarities and differences in the biochemical make-up of organisms that can help distinguish differences and similarities

Microevolution (DDT & Mosquitoes / Antibiotics & Bacteria)

The study of the geographical distribution of organisms which can help ascertain where a species may have originated from.