Biology Flashcards
Cell membrane
controls the movement of substances in and out of the cell
cytoplasm
It is where many of the chemical reactions happen.
nucleus
Contains genetic material, including DNA, which controls the cell’s activities
mitochondrion
Organelles contain the enzymes for respiration, and where most energy is released in respiration.
cell wall
strengthens the cell and supports the plant
chloroplast
Organelles that contain the green pigment, chlorophyll, which absorbs light energy for photosynthesis.
vacuole
Filled with cell sap to help keep the cell turgid
ribosomes
Tiny structures where protein synthesis occurs.
plasmid DNA
Used to transfer genetic material from one cell to another
chromosomal DNA/no ‘true’ nucleus
DNA holds the genetic information of the cell floats freely.
Diffusion
The movement of molecules from an area of higher concentration to an area of lower concentration.
osmosis
The movement of water molecules across a selectively permeable membrane from a region of higher water concentration to a region of lower water concentration.
active transport
move molecules against a concentration gradient.The process requires energy
levels of organisation
cells → tissues → organs → organ systems
Organelle
A specialised unit within a cell which performs a specific function
Cell
The basic building block of all living organisms
Tissue
A group of cells working together to perform a shared function, and often with similar structure
Organ
A structure made up of groups of different tissues, working together to perform specific functions
Organ System
A group of organs with related functions, working together to perform certain functions within the body
mitosis
division leading to two daughter cells that have the
same number of chromosomes so are genetically identical to each other and the
parental cell
interphase
the cell grows and
DNA is copied
role of mitosis
growth by increasing cell numbers,
repair of tissues, replacement of worn out cells and asexual reproduction
cancer
mutations in cells that lead to uncontrolled
growth and division
meiosis
division that produces genetically different daughter cells which have half a set of chromosomes.
role of meiosis
formation of gametes in sexual reproduction
asexual reproduction
involves one parent and that
offspring are genetically identical when no mutations occur.
sexual reproduction
involves two parents and
offspring are genetically different in relation to each other and the parents,
leading to (increased) variation.
Type of chromosomes for females and males
females are XX and males
are XY
site of genetic material
nucleus
gene
a section of DNA which controls part of a cell’s chemistry - particularly protein production
allele
Different forms of the same gene.
dominant
An allele that always expresses itself whether it is partnered by a recessive allele or by another like itself
recessive
A recessive gene will remain dormant unless it is paired with another recessive gene
heterozygous
a genotype in which the two alleles for a particular characteristic are different
homozygous
a genotype in which the two alleles for the characteristic are identical
phenotype
visible characteristics of an organism which occur as a result of its genes
genotype
alleles that an organism has for a particular characteristic
chromosome
The structure made of DNA that codes for all the characteristics of an organism
genome
entire genetic material (DNA) of an organism
DNA structure
A polymer made up of two strands forming a double helix. Made from four different nucleotides.
genetic code
‘read’ as triplets, and that each
triplet codes for an amino acid.
What do genes carry?
code for proteins
protein synthesis
production of proteins from amino
acids
mutation
change in the DNA
mutations effect?
no effect on the phenotype, some will have a
small effect, whilst occasionally others will determine the phenotype
process of genetic engineering
Enzymes are used to isolate the required gene, this gene is inserted into a vector, which is usually a bacterial plasmid or a virus.
The vector inserts the gene into required cells.
The genes are transferred to animal, plant or microorganism cells, during early development. This allows them to develop with the desired characteristics.
genetic engineering
modifying the genome of an organism by introducing a gene from another organism to result in a desired characteristic
examples of genetic engineering
Bacterial cells have been genetically modified to produce substances such as human insulin
genetically modified crops include those that are resistant to insect attack or are herbicide resistant
Scientists have added a gene to wild rice that makes it produce beta carotene
benefits and risks of using genetic engineering
The advantage of golden rice is that it can be used in areas where vitamin A deficiency is common, so it can help prevent blindness
ethical issues and possible health risks of genetically modified food
embryonic stem cell
A type of stem cell found in the embryo, capable of dividing into almost any cell type
functions of stem cells
A cell found in foetuses, embryos and some adult tissues can give rise to a wide range of other cells
Cells as animals mature
lose the ability of stem cells
benefits of using your own stem cells
no rejection
no need to find a donor
no need for tissue typing
Clinical issues of stem cells
no guarantee how successful
difficulty in obtaining and storing a patient’s embryonic stem cells
Ethical issues of stem cells
is it right to create embryos for therapy, and destroy them in the process?
Embryos could come to be viewed as a commodity, and not as an embryo that could develop into a person.
Selective breeding
rare disease genes can be unknowingly selected as part of a positive trait eg a high percentage of Dalmatian dogs are deaf
can create physical problems in specific organisms, eg large dogs can have faulty hips due to not being formed correctly
Enzymes
proteins that function as biological catalysts
Catalysts
speed up a chemical reaction without being changed by the reaction
