Biology Flashcards
What is the Cell Theory?
- All living things are made up of one or more cells
- The cell is the basic unit of life
- All cells come from pre-existing cells
Describe the cell membrane and its functionality
Separates the inside of the cell from the external environment; controls the flow of materials into and out of the cell
Describe the cytoplasm and its functionality
Jelly-like fluid filling the cell includes the cytosol, the organelles and other life-supporting materials, such as sugar and water, all contained by the cell membrane; gives the cell its shape, supports many necessary functions within the cell
Describe mitochondria and their functionality
(singular: mitochondrion) Powerhouse of the cell; where energy is released from glucose to fuel cell activities
Describe ribosomes and their functionality
Some float in the cytoplasm, some are attached to the rough endoplasmic reticulum; help to produce proteins, which make up much of a cell’s structure and are required for activities necessary for the cell’s survival
Describe the endoplasmic reticulum and its functionality
A network of membrane-covered channels that transport materials made in the cell; is connected to the nucleus
Describe vesicles and their functionality
Membrane-covered sacs that transport and/or store materials inside the cell and sometimes help these materials cross the cell membrane to enter or exit the cell
Describe golgi bodies and their functionality
Sort and package proteins and other molecules for transport out of the cell
Describe the nucleus and its functionality
Controls all the cell activities; contains DNA/instructions for the cell, its functions and lifespan
Describe vacuoles and their functionality
Contain water and other materials and are used to store or transport small molecules; plant cells tend to have one large vacuole; animal cells may have several smaller vacuoles
Describe the cytoskeleton and its functionality
Filaments and tubules that provide a framework for the cell, helping it maintain its structure and providing “tracks” along which vesicles and organelles can move.
Describe the cell wall and its functionality
A tough, rigid structure lying just outside a plant cell’s membrane; provides support for the cell
Describe chloroplasts and their functionality
Trap energy from the sun to make glucose, which is broken down in the mitochondria to power cell activities (animals must get glucose from the food they eat)
Cell membrane - plant, animal or both?
both
Cytoplasm - plant, animal or both?
both
Mitochondria - plant, animal or both?
both
Ribosomes - plant, animal or both?
both
Endoplasmic Reticulum - plant, animal or both?
both
Vesicles - plant, animal or both?
both
Golgi Bodies - plant, animal or both?
both
Nucleus - plant, animal or both?
both
Vacuoles - plant, animal or both?
both
Cytoskeleton - plant, animal or both?
both
Cell wall - plant, animal or both?
only plant
Chloroplast - plant, animal or both?
only plant
What is the process of cellular respiration?
The process of obtaining energy to fuel all cell activities, occurring in the mitochondria.
What is the formula for cellular respiration?
C(6)H(12)O(6) + 6O(2) —> 6CO(2) + 6H(2)O + ATP/energy
What is the formula in words for cellular respiration?
glucose + oxygen –> carbon dioxide + water + energy
What is the difference between rough and smooth endoplasmic reticulum?
Rough have ribosomes, smooth don’t have ribosomes
Describe chromosomes and their functions
Each cell has a complete set, each species has a specific number of chromosomes (humans - 46 or 23 pairs). Come in pairs and contain master instructions.
What does the chromosome combo XY mean?
Male
What does the chromosome combo XX mean?
Female
What is a karyotype?
Number, appearance and arrangement of chromosomes in an organism
What does DNA mean?
Deoxyribonucleic Acid
What is DNA?
Makes up chromosomes; DNA and its associated proteins are called chromatin. DNA is divided into segments called genes which code for proteins that have certain functions. only 3% of DNA are genes, remaining 97% is referred to as junk DNA. Made up of monomers (unit of counting) called nucleotides. DNA has a double helix structure.
What are the four nucleotides and what are they paired with?
Adenine pairs with Thymine (AT)
Cytosine pairs with Guanine (CG)
What is the genetic code?
The sequence in which nucleotides are arranged. All humans have a unique genetic code except for identical twins. This determines what protein is being produced and when.
What methods can be used for testing genetic disorders? Describe them.
Blood tests are the less invasive method. They indicate presence or absence of specific proteins (Ex. phenylketonuria/PKU in babies).
Amniocentesis tests are more invasive and discover abnormalities in the karyotype of a fetus. To do so, a needle is inserted into the amniotic sac to extract cells but could hit fetus. This test tells whether there are too many (trisomies) or too few cells (chromosome deletions).
Why is it possible to alter genes?
Because A, C, T, and G produce the code for all organisms and can be read by any living thing.
What are GMOs?
Genetically modified organisms have another organisms genes spliced into their own.
What are transgenic organisms?
Organisms made to produce required organs (shortage of organs for transplantation).
What are some issues with gene altering?
Not natural, so consequences have not been fully studied Making transgenic organisms is not ethical - what happens to the rest of the organism?
What is cloning?
The process of producing identical offspring from genes, cells, or and entire organism. The genetic code of the produced cell is identical to that of the parent cell.
What is a gene mutation and what does it do?
A permanent change in the DNA sequence of a gene; an abnormality. This can change the structure of the protein produced, possibly changing the function. Mutations can be passed to offspring or some are only effective in one individual. Range in size (cell to segment of chromosome) and occur by chance.
What are mutagens?
Factors that damage DNA and cause mutations in the nucleotide sequence. (tar, mercury, radiation)
What is a polymorphism?
A genetic change that occurs in more than 1% of the population (a common enough variation in DNA to be considered normal)
How can mutation be beneficial? Give an example
A mutation can help a species thrive in their environment. For example, in pre-industrial England, the peppered moth survived better than the black moths because a single gee mutation gave them the same colouring as tree trunks.
What is cell reproduction?
The process by which new cells are formed (different process and reason for unicellular than for multicellular)
What is the process of cell reproduction for unicellular organisms?
only one parent, one cell forms two daughter cells with identical DNA, only done to multiply the species
What is the process of cell reproduction for multicellular organisms?
requires two parents, only half of DNA from each parent, reproduce to multiply, growth, repair and functionality
When does a cell divide?
When it has grown so much that the surface area to volume ratio is too large, a cell needs to divide to maintain functionality
How do nutrients, oxygen and water pass get in the cell?
They pass through the selectively/semi-permeable cell membrane though diffusion and osmosis
What is diffusion?
Particles move from an area of high concentration to an area of low concentration (spread out within a space)
What is osmosis?
The movement of water from an area of high concentration to an area of low concentration. Same as osmosis but only considering water, so there might be a higher particle concentration where they move to, but the water will be less concentrated.
Why does large cell size affect functionality?
Nutrients are unable to reach all organelles and there is more production of waste when a cell has an unbalanced surface area to volume ratio.
What is DNA replication?
A process when parent cells precisely replicate every single chromosome before dividing
What happens when there is an error in DNA replication?
The error is usually detected and fixed by proofreading and repair proteins.
What is mitosis?
(A.K.A. karyokinesis) The first stage of cell division, when the genetic material (nucleus) divides into two equal parts (made up of PMAT)
What does PMAT stand for?
Prophase, Metaphase, Anaphase, Telophase
What occurs in prophase?
Proteins start to form (centrosomes), centrosomes spread to opposite sides of cell and form spindle fibres, the nuclear membrane and nucleolus (organelle in nucleus) start to disintegrate
What occurs in metaphase?
longest phase of mitosis - centrosomes reach opposite ends, chromosomes move to middle of cell and line up at equator, very condensed
What occurs in anaphase?
shortest phase of mitosis - proteins holding chromatids together break apart, spindle fibres contract and pull sister chromatid to opposite poles, cell elongates (watermelon shape)
What occurs in telophase?
spindle fibres disappear, chromosomes become less condensed and reappear as threads, a new membrane and nucleolus form to start the separation into two new cells (animal cell- two new cells begin to form when the cell is pinched in half)
What is cytokinesis?
The second stage of cell division in which contents of a cell, the cell wall (plant cells) and organelles are divided
What occurs in animal cell cytokinesis?
whole cell membrane pinches around two daughter cells/nuclei and splits to form two cells, completing cell division
What occurs in plant cell cytokinesis?
Golgi body produces vesicles that form a line in the middle of the cell, forming a cell plate. This new cell wall grows to join old cell wall. A new membrane forms inside the cells
How are cells differentiated?
They are specialized because each cell only uses 10% of its genes
What factors affect the life span of a cell?
Exposure to hostile elements: physical (abrasion, motion), chemical (toxic, acidic, basic substances), function (protect against pathogens/bacteria that pose risk of disease)
What determines what elements a cell is exposed to?
the type of cell it is (ex.stomach cells die quickly due to high exposure)
What do proteins have to do with the cell cycle?
they share info about cell health and abundance to control the growth and division cells undergo
What are the two stages of the cell cycle?
cell division (mitosis and cytokinesis), and interphase
What is interphase?
The growing stages in the life of a cell
What are the stages of interphase?
2 growth stages and 1 DNA replication stage: first Gap 1 (G1), where cells engage in normal activities and the cell grows, then DNA replication, where DNA is replicated in preparation for cell division and ending when there are 92 chromosomes, then Gap 2 (G2), where cells do the same as G1
When are the cells checked for healthiness?
First at the end of G1, when unhealthy cells will exit and suicide (apoptosis), then again after G2, then after mitosis
What happens when the cells are checked?
Proteins act as stop signals and do not let any cells continue if: the cell doesn’t have enough nutrients for growth, the DNA is not replicated (after G2), or DNA is damaged, or after mitosis if the cell is not needed.
What is necrosis?
When a cell becomes damaged and suddenly dies: physical trauma or exposure can make a cell leak. (a cell dies due to injury, disease or any other damage, it is inevitable)
What is apoptosis?
“Cell Suicide” - a preprogrammed system of events eliminates cells without releasing contents of the cell and harming other healthy cells. The useful contents of the cell are packaged to be used by other cells before the code in genes for protein to kill cells goes into effect. (Ex. skin between webbed finger and toes on humans)
What happens when apoptosis doesn’t work properly?
Cells that should die stay in the cycle and become immortal. This causes diseases such as cancer and leukemia. (the cells form clumps called tumours after telomerase signals for the cells to never stop dividing). This would have to happen constantly to become cancerous, but happens mostly when DNA is mutated and makes faulty proteins.
What happens when apoptosis happens too often/works overly well?
Too many cells are killed and tissue is damaged, causing strokes and neurodegenerative disorders such as Alzheimer’s.
How can mitosis itself cause mutation?
Each time a cell’s DNA is copied, there are errors, but these are usually fixed by or repair systems
Describe the structure of DNA
DNA has a double helix structure constructed of nucleotides, deoxyribose sugar and phosphate. Nucleotides are partially made up of pairs of nitrogen bases; adenine pairs with thymine, and guanine pairs with cytosine. The nucleotides make up the steps of the ladder, with the outside made up of a repeating pattern of sugar and phosphate. 97% of this is junk DNA, the rest makes up your genes
What is the function of the nucleolus?
This structure is made up of proteins and ribonucleic acids (RNA). Its main function is to produce and rearrange ribosomes
What is the function of genes?
Code for proteins that perform specific functions: building blocks, transport.
Who first proposed the double helix structure of DNA?
Francis Crick and James Watson
What are chromosomes made up of?
DNA
How many genes are in one strand of DNA?
Hundreds of thousands of genes
What are sister chromatids?
Two identical strands joined by a common centromere as a result of a chromosome that duplicated during the S phase of the cell cycle (half of chromatin)
What is the ‘s’ phase of the cell cycle?
DNA replication
What makes up a gene’s code?
The order/sequence of nucleotides
What is the centromere?
The centromere is the part of a chromosome that links sister chromatids (the middle of the x)
