Science Biology - Inheritance and evolution Flashcards
Antibiotics
Antibiotics are used to treat or prevent some types of bacterial infection. They work by killing bacteria or preventing them from spreading. Antibiotics kill bacteria by stopping cell wall synthesis or even interfering with protein synthesis. (most important function in any cell, if stopped the cell is destroyed) sometimes.
Antibiotic Resistance
Some antibiotics are becoming less effective because these bacteria are mutating to become resistant to their antibiotics and through natural selection the unresistant bacteria are being killed off leaving the resistance bacteria, which means the antibiotics won’t be affective anymore.
DNA
Deoxyribose Nucleic Acid. DNA is often called the blueprint of life. Because it contains instructions needed for an organism to grow, develop survive and reproduce. In simple terms, DNA contains the instructions for making proteins within the cell, which are essential for all life.
The structure of DNA is a double Helix. It is a polymer chain made up of monomers called nucleotides which consist of a phosphate group, nitrogen base and deoxyribose sugar.
RNA
Ribonucleic Acid. RNA is single-stranded. It has the bases A-U-C-G. There are three types of RNA. rRNA, rRNA and tRNA. RNA turns genetic information into protein.
mRNA
Copies the genetic code from DNA to RNA bases. IT moves from the nucleus to the cytoplasm from the cell. This process is called transcription.
rRNA
It is located in the cytoplasm of the cell. It is the components of ribosomes and it directs the translation of mRNA into proteins. It is exported to the cytoplasm to help translate the information in messenger RNA (mRNA) into protein
tRNA
It is located in the cellular cytoplasm. Transfer amino acids to the ribosomes to assemble proteins. When a tRNA recognizes and binds to its corresponding codon in the ribosome, the tRNA transfers the appropriate amino acid to the end of the growing amino acid chain.
Nitrogenous Bases
The Nitrogenous bases in DNA are Adenine, Thymine, Guanine, Cytosine and the nitrogenous bases in RNA are Adenine, Uracil, Cytosine, Guanine.
Phosphate
It is both In DNA and RNA. It along with the deoxyribose sugar are considered the backbones of DNA, with the nitrogenous bases sticking out of them.
Deoxyribose sugar
It is both In DNA and RNA. It along with the phosphate groups are considered the backbones of DNA, with the nitrogenous bases sticking out of them.
Cell Division
A single parent cell divides into two daughter cells, each with a complete copy of the genetic material of the parent and with the capability to divide again. Cells must also divide because old cells die and need new cells to replace them. Cell division is split into three main stages: interphase, mitosis and cytokinesis
Interphase
Cell grows into its mature size, makes a copy of its DNA, and prepares for division. This is the longest stage of cell division in any cell. There are three main phases of interphase: G1, S and G2.
Interphase: G1
This is the growth phase:
Cell doubles in size
Cell produces all the structures it needs to carry out its functions (organelles replicated)
Think of this phase as the cell just living its normal life.
Interphase: S
This stage consists of the synthesis of protein and the replication of DNA:
Cell makes a copy of its DNA (replication)
This happens because the new cells needs all of the instruction for its function and survival.
Think of this phase as placing the DNA in a copy machine.
Interphase: G2
This is the stage where the cells prepare to divide:
Cell prepares to divide
Cell produces structures needed for cell division.
Think of this phase as the cell double checking everything it needs to divide.
Mitosis
During mitosis the cells copied genetic material separates, and the cell prepares to split into two cells. This allows the cells genetic material to pass into new cells. The resulting daughter cells are genetically identical.
Mitosis is the cell division of somatic cells (bodily cells) and does not include the egg cells.
Prophase
First stage of mitosis:
The nucleus disappears
Spindle fibres form in the cytoplasm
Spindle fibres attach to sister chromatids to separate the chromosomes.
Metaphase
Second stage of mitosis:
The sister chromatids are pulled to the centre of the cell
They (chromatids) line up in the middle of the cell with the spindle fibres attached to them
Anaphase
Third stage of mitosis:
The spindle fibres begin to shorten (to pull them apart)
The sister chromatids are pulled to the opposite ends of the cell.
Telophase
Last stage of mitosis:
Where the sister chromatids arrive at the opposite poles of the cell and begin to unravel
New nucleus begins to form.
Cytokinesis
This is the last stage of the cell division process:
The division of the cytoplasm
Results in two separate daughter cells with identical nuclei.
Meiosis
Is a type of cell division that reduces the number of chromosomes in the parent cell by half (or produces a haploid number of chromosomes. Haploid chromosomes = 23 chromosomes) and produces four gamete cells.
The process is required to produce egg and sperm cells for sexual reproduction. During reproduction, when the sperm and egg unite to form a single cell, the number of chromosomes is restored in the offspring.
Meiosis 1
1 parent cell splits into two
Chromosomes are replicated to form sister chromatids. Sister chromatids are genetically identical and joined at centromere.
Prophase 1
Homologous chromosomes become closely associated in synapsis
Crossing over occurs. Crossing over is a complex series of events in which DNA segments are exchanged between Non sister or sister chromatids.
Metaphase 1
In metaphase I, the homologous pairs of chromosomes line up in the middle of the cell.
Anaphase 1
Homologous pairs of chromosomes split to either poles of the cell. Sister chromatids stay together. Basically if there are two pairs of chromosomes then either pair gets dragged by the spindle fibres to either end of the cell.
Feature 2 of meiosis.
Crossover: Parts of the chromatid in each chromosome swap. It kind of makes a remix version of the chromosome.
Telophase 1
The cell splits into newly formed cells. These cells are haploid. Each chromosome pair in the cells has non identical sister chromatids.
Meiosis 2
2 parent cells split into a total of 4 daughter cells. Meiosis 2 follows similar steps to mitosis. Meiosis 2 starts with 2 diploid cells with 2 pairs of chromosomes and sister chromatids that are non-identical.
Zygotes
Zygote, fertilized egg cell that results from the union of a female gamete (egg, or ovum) with a male gamete (sperm). As a results, a zygote contains a diploid number of chromosomes (46).
Gametes
A gamete is the male or female reproductive cell that contains half the genetic material of the organism. When two human gametes meet — that is, a sperm cell and an ovum — you get a zygote, a fertilized egg.
Somatic Cells
A somatic cell is any cell that makes up an organism, except for a reproductive cell.
Haploid
Haploid is the term used when a cell has half the usual number of chromosomes. 23 chromosomes for humans.
Diploid
In diploid cells, one set of chromosomes is inherited from the individual’s mother, while the second is inherited from the father. Contains a total of 46 chromosomes like most human beings.
Animal cell
Has all the normal cell organelles as a plant cell except:
Chloroplast
Cell wall
Large vacuoles.
Plant cell
Has all the normal cell organelles as an animal cell except:
Centrioles and centrosomes.
Small Vacuoles
Cell organelles
Organelle A specialized subunit within a cell that has a specific function.
Mitochondria
The powerhouse of the cell.
Nucleus
The brain of the cell. It is nuclear envelope that contains the DNA/nuclear material of the cell. It has the chromatin and the DNA - contains the instructions for protein synthesis. It produces ribosomes.
Cytoplasm
The jello substance where the cell organelles are floating.
Chloroplast
Organelle that carries out the process of photosynthesis. Its like a light sensor where photosynthesis occurs.
Endoplasmic Reticulum
The site where cell membrane and exported material is made. Two types: Smooth – Ribosome free and functions in poison detoxification. Rough – Contains ribosomes which is the protein factory of the cell. (black dots vs no black dots). Cell membrane and endoplasmic reticulum work together to export things.
Ribosome
A ribosomes is a small organelle involved in the process of making protein, which is called protein synthesis.
Golgi apparatus
A series of flattened sacs that modifies packages, stores, and transports materials “like protein and lipids” out of the. cell.
Cytoskeleton
Framework of the cell. They support the cell giving it its shape and help the movement of its organelles.
Vacuole
They are large central, and they have fluid-filled organelle.
Plant cells: Help maintain water balance.
Animal cells: to remove waste products in the cell
Cell membrane
The boundary of the cell and its organelles. Made of hydrophobic and hydrophilic components (likes vs dislikes water). Found in both plant and animal cells.
Cell wall
Provides strength and protection for the cell.
Lysosome
Contains digestive enzymes.
Prokaryotic cells
Prokaryotic cell: Cell membrane, cytoplasm. Simple cell.
Single-celled organisms
They are organisms without a cell nucleus.
Most are unicellular but some prokaryotic cells are multicellular.
Bacteria/archaea
Eukaryotic cells
Eukaryotic cell: Cell membrane, cytoplasm, mitochondria, nucleus etc. More complex.
Two kinds of cells: Plants and Animals.
Has a nucleus
Linear and Circular DNA
The main difference between linear and circular DNA is that linear DNA consists of two ends in each side, whereas circular DNA does not have an end. Furthermore, the genetic material in the nucleus of eukaryotes is linear DNA while the genetic material of prokaryotes, as well as mtDNA and cpDNA, are circular DNA.
Nucleotides
A nucleotide is the basic building block of nucleic acids. RNA and DNA are polymers made of long chains of nucleotides. A nucleotide consists of a sugar molecule (either ribose in RNA or deoxyribose in DNA) attached to a phosphate group and a nitrogen-containing base.
Polymer
Polymers are materials made of long, repeating chains of molecules.
Monomer
A molecule that can be bonded to other identical molecules to form a polymer.
Watson Model for DNA
Watson and Crick proposed that the DNA is made up of two strands that are twisted around each other to form a right-handed helix, called a double helix. Base-pairing takes place between a purine and pyrimidine: namely, A pairs with T, and G pairs with C.
Pyrimidine
The shapes for the four nitrogenous bases are different. There are two kinds of Bases in DNA: Pyrimidines are single ring bases.
Cytosine C - Pyrimidines
Thymine T - Pyrimidines
Purine
Purines are double ring bases.
Adenine A - Purines
Guanine G - Purine
Protein Synthesis
Protein synthesis is the process in which cells make proteins. It occurs in two stages: transcription and translation.
Human Chromosomes
Humans have 46 chromosomes each. Chromosomes are tiny structures inside cells made from DNA and protein. They are condensed chromatin and they are found in the nucleus of the cell.
Chromatids
Chromatids are the daughter strands of a duplicated chromosome which are joined by a single centromere. When the centromere divides, the chromatids become separate chromosomes. (These are the two little strands below and above the centromere).
Chromatin
Chromatin is the material that makes up a chromosome that consists of DNA and protein.
Genes
A particular region of DNA that controls specific trait like tongue tolling or ear lop.
Dominant Genes
The trait that first appears or is visibly expressed in the organism is called the dominant trait.
Recessive Genes
The trait that is present at the gene level but is masked and does not show itself in the organism is called the recessive trait.
Alleles
Alleles are different versions of the genes.
Genotype
Genotype is the collection of genes responsible for the various genetic traits of a given organism. Genotype refers specifically to the genes, not the traits; that is, the raw information in an organism’s DNA. Example: Bb BB, bb
Phenotype
A phenotype is an individual’s observable traits, such as height, eye color, and blood type. This is the physical appearance.
Homozygous
Homozygous is a genetic condition where an individual inherits the same alleles for a particular gene from both parents. BB, bb
Heterozygous
Heterozygous refers to having inherited different forms of a particular gene from each parent. Bb
Genetic Variation
Genetic variation refers to diversity in gene frequencies. Genetic variation can refer to differences between individuals or to differences between populations. Mutation is the ultimate source of genetic variation, but mechanisms such as sexual reproduction and genetic drift contribute to it as well.
Evolution is a change in the genotype of the population over time.
Phenotypic differences between species reflects genetic differences between species = genetic variation across species.
The origin of genetic variation is partly mutation.
Genetic Mutation
A permanent alteration to a DNA sequence (A-T, C-G)
Offspring has DNA that is different from both parents.
The types of mutation: substitution, inversion, addition, deletion
Genetic Mutation: Deletion
In genetics, a deletion (also called gene deletion, deficiency, or deletion mutation) is a mutation in which a part of a chromosome or a sequence of DNA is left out during DNA replication.
Genetic Mutation: Addition
GGTCTC – GGTGCTC
A frame shift mutation. Lots of codons are affected because you are adding a new base to the sequence. This could result in the production of completely new amino acids.
Genetic Mutation: Substitution
GGTCTCCT – GGTCACCT
This will affect the mRNA and then that would result in a new amino acid being produced.
Substitution will only affect a single codon. Their effect may not be serious unless they affect an amino acid that is essential for the structure and function of the finished protein molecule (e.g. sickle cell anemia)
“Stop” amino acid means nonsense amino acid. This is a disaster. If a stop codon was produced in the middle of the gene, then the protein formed would be too short, and almost certainly wouldn’t function properly.
Colour Blindness
Colour blindness is a deficiency where some people can’t see certain colours. The cause of this is the mutations in the following genes: OPN1LW, OPN1MW, and OPN1SW.
The proteins produced in this gene are found in the retina and are necessity for colour vision. When people have malfunctioning cones (mutations in the genes for the cones) the wavelengths of the light overlap each other making it harder for the cones to distinguish between the different pigments.
Natural Selection
Survival of the fittest.
It eliminates the less desirable traits and replaces it with the more favorable traits.
There are three types of natural selection: disruptive, directional and stabilizing.
Disruptive
Chooses the extreme ends and cancels out the medium (amongst black, grey and white bunnies in a forest, this type of natural selection would cancel out the grey bunny and keep the black and white bunny because it wouldn’t be able to camouflage in forest conditions.)
Directional
Chooses the extreme favorable trait (tall vs short giraffes, this natural selection would choose tall giraffes and completely kill the short giraffes.)
Stabilizing
Chooses the option in between. (tall, medium, short. This natural selection would choose medium)
Down Syndrome
Extra chromosomes.
Typically a baby is born with 46 chromosome. Down syndrome babies have an extra pair of chromosome 21.
In children with Down syndrome, one of the chromosomes doesn’t separate properly. The baby ends up with three copies, or an extra partial copy, of chromosome 21, instead of two. This extra chromosome causes problems as the brain and physical features develop.
Symptoms associated with the syndrome include mental retardation, distinctive facial characteristics, and increased risk for heart defects and digestive problems, which can range from mild to severe.
DNA Replication
DNA replicate occurs during the Interphase of cell division. DNA replication does not happen during cell divisions.
The key components in DNA replication: The majority of these are enzymes: Helicase, DNA polymerase, Primase and Ligase.
Helicase
The first step of DNA replication:
The unzipping enzyme. It basically unzips the double helix at the origin.
Ligase
The last step of DNA replication:
It helps glue DNA fragments together.
DNA Polymerase
The second step of DNA replication:
The builder. This enzyme replicates DNA molecules to build a new strand of DNA.
Primase
The third step of DNA replication:
The initializer. It guides the DNA polymerase on where to get started. Primase makes a Primer so that DNA polymerase knows what to do. Primer is made up of a small piece RNA.
Feature 1 of Meiosis
Synapsis: Pairing of homologous chromosomes
Feature 3 of Meiosis
Reduction Division:
In reduction division, the chromosome number is reduced from diploid (46 chromosomes) to haploid (23 chromosomes). Also known as first meiotic division and first meiosis.
