Topic 3 Flashcards
What are the two type of cells?
Prokaryotic, eukaryotic
What is often prokaryotic?
Bacteria
What do prokaryotic cells not have?
Nuclei or membrane bound organelles
Features of prokaryotic cells
Ribosome, circular DNA, cell membrane, cell wall, cytoplasm, unfolds in membrane, plasmid, capsule, polo, flagellum.
Are prokaryotic or eukaryotic cells larger?
Eukaryotic
Structure and role of mitochondria?
Cristae folds, matrix inside. Used for aerobic respiration.
Structure and role of nucleus?
Nuclear envelope, nuclear pores, nucleolus, chromosomes. Synthesis of proteins.
Structure and role of nucleolus?
Dense within nucleus. Ribosomes are made.
Structure and role of rough endoplasmic rectillium.
Flattened membrane bound sacks with ribosomes attached. Proteins made an transported through endoplasmic rectillium.
Structure and role of ribosomes?
RNA and a protein. Protein synthesis.
Structure and role of smooth endoplasmic rectillium.
Flattened membrane bound sacks. Makes lipids and steroids.
Structure and role of Golgi apparatus?
Flattened membrane bound sacks, decreasing in size, vesicles. Modifies proteins and moves them into vesicles for transport.
Lysosomes structure and role.
Sacks of digestive enzymes, single membrane. Breaks down unwanted substances/structures.
Centriole roles and structure?
Hollow cylinder pairs, 9 microfibres each, forms spindle fibres.
What structures contain their own DNA?
Mitochondria, chloroplasts.
What is the process of making a protein?
DNA to tRNA to mRNA to ribosome, protein made,move through ER to get shape, vesicles formed, then fuses with Golgi apparatus, protein is modified, vesicles made, vesicles fuses with cell membrane, protein released. (Extra cellular eg enzyme)
How does the ovum move
Wafted along oviducts by ciliated cells and muscular contraction
What does the cytoplasm of the ovum contain?
Protein and lipid food stores for the embryo.
How do sperm get the energy to swim
A mitochondria inside
How to sperm move through the cell
Flagellum. muscular contraction. Chemicals released by ovum.
What is the acrosome reaction?
Acrosome swells and fuses with the surface membrane of sperm. It then releases digestive enzymes which breaks the zone pellucidia.
The acrosome is an example of what?
Lysosomes.
What is the cortical reaction?
The sperm fuses with and penetrates the cell membrane of the egg. The ovum releases chemicals which causes the zona pellucidia to thicken. This prevents other sperm from entering the egg.
What happens after the cortical reaction?
The sperm nucleus and the egg nucleus fuse to produce a fertilised egg.
What is a fertilised egg called?
A zygote.
What is the structure of the ovum?
Lipids, lysosomes, cytoplasm, haploid nucleus, cell membrane. Surrounded by the Zona pellucidia, his us all then surrounded by follicle cells from ovary.
Structure of a sperm?
Acrosome, haploid nucleus, mitochondria, flagellum.
What do the 23 pairs of chromosomes consist of?
22 homologous pairs and one sex pair
What is mitosis used for?
Cell repair and growth, asexual reproduction.
Where does meiosis happen?
Ovary, flowering plants, and testes
Why is meiosis good
It creates haploid cells and genetic variation.
What is independent assortment?
The way a pair of chromosomes line up
What is crossing over?
Chromosomes come together and 4 chromatids come into contact at contact points. The chromatic breaks, exchanges and rejoins the DNA of non sister chromatids.
What is the breaking point in crossing over called?
Chaisma
What is linkage of genes?
If a gene has a same locus on a chromatid they are likely to be passed on together.
Who gave evidence for linkage?
Gregor Mendel
What did Gregor Mendel show in his experiment. What could be concluded?
During f1 only one pair of characteristics were shown out of four. And f2 all four were shown. Genes were linked.
What is sex linkage?
Genes that are passed on on y or X chromosomes.
Example of sex linkage? Why?
Colour blindness in males. Recessive on X chromosome, but as males only have one x it becomes dominant
What are the three stages of interphase?
G1, S, G2
How does DNA condense?
DNA winds around and binds to histone proteins. These both cool to form chromatin fibre, this then starches to a protein scaffold on one side. This form loops of chromatin. This structure folds to make the condensed chromosome.
What happens in interphase?
Protein synthesis due to unraveled chromosomes, DNA replication, organelles are synthesised.
What happens in prophase?
Chromosomes condense, two chromatids per chromosome. (Four arms) joined at the centromere. Centrioles move to opposite ends of the cell and spindle fibres form between them. The widest part of the spindle is the equator. Nuclear envelope breaks down. Nucleolus disappears.
What happens in metaphase
Centromeres attach to spindle fibres at the equator
What happens in anaphase?
The centromeres split and spindle fibres shorten. This pulls a chromosome into two chromatids. These are pulled to opposite poles. Spindle fibres break down.
What happens in telophase?
Chromosomes unravel, two nuclear envelopes form. Two sets of genetic material are now in separate nuclei.
What happens in cytoplasmic division?
Ring of protein filaments contract and cell membrane constructs. Two cells are formed. In plants a new cell plate is formed.
In a plant cell how is a cell wall formed?
Cytoplasmic division. The Golgi produces vesicles containing genetic material, the move along microtubioles and fuse
How many replications does a zygote go through until it is totipotent?
- 8 total cells
What does totipotent mean
It can develop into any cell
How long do cells stay totipotent
Up to 14 days.
What is a blastocyst
Hollow ball of cells
When is a blastocyst formed
5 days after contraception
What does the blastocyst form into
Outside turns into placenta and inner turns to embryonic tissue
What type of cells are the inner cells of the blastocyst
Pluripotent
What does pluripotent mean
They can form into most cells but not all
What are multi potent cells
They can develop into similar cells of the same system
Why can plants produce clones
They are totipotent and have the ability to differentiate.
What is the process of tissue culture
Ex-plants are surface sterilised and placed on a agar medium containing nutrients and growth hormones.
These cells divide to form a mass of undifferentiated cells called a callus
The growth regulators can be altered to allow the callus to develop into a small group of cells
These then develop into plants that are genetically identical clones.
Advantages and disadvantages of tissue culture
+ large number of plants very fast for food or desirable quality.
-less genetic variation, leading to easy extinction
Where are stem cells for research taken from
Unused ivf
What type of cells are stem cells used for research.
Pluripotent
What could happen with stem cells and patents
Rejection
What is therapeutic cloning
Nucleus from patients somatic cell put into an ovum. Electric shock. Diploid cell that acts as a zygote.
What allowed more research into stem cells
Animal- human embryos
What is ipsc
Somatic cells to pluripotent
What is an animal human embryo
Human nucleus. Animal ovum.
What does ipsc prevent.
Rejection and ethical issues.
How was the nucleus shown to control cell development
Different Agal cells were grown. Hats were removed and stalks swapped. The intermediate heads that grew were a mix of the two species. The hate we’re then moved again and hates that coincided with the rhizoid grew
What did the agal cell experiment show about the intermediate hats
mRNA carries the protein that control structure, that why the intermediate hats were mixed
How was gene expression shown
mRNA was taken from undifferentiated cells and differentiated cells. The differentiated cells had complimentary DNA made, the mRna was then digested. The complimentary DNA and the mrna from the undifferentiated cell was mixed. Some double helixes formed which showed that only some genes were expressed at a time.
What happens when genes are switched on
Mrna is produced which translates into a Specific protein.
When the genes are switched off what is present? How does this work?
Methyl group
The group stops RNA polymerase bonding to the gene, this means no transcription so no mRNA
Histones are tightly wrapped in present of the methyl group. This tightness prevent the rna polymerase from bonding so no mRNA so no protein
What is the epigenome
The types of epigenetic markers
What is the genome
All the DNA containing a full set of genes
What is the lac operon model with no lactose
When lactose is absent the repress of bonds to the operator so rna polymerase can not bind. The gene can then not be transcribed
What is the lac operon model with lactose present
Lactose bonds to the depressor so rna polymerase can bind to promoter region. This allows transcription and translation so an enzyme so formed. Gene is on.
A regulator protein is also required
What is polygenic inheritance. Distribution.
A number of genes are involved in the inheritance of a characteristic.
Continuous.
What does multifactorial mean
Both genetic and environmental factors are involved.
What is melanin
A dark hair pigment
Where is melanin made
Melanocytes
What activates melanin production
MSH
What transports melanin
Melansomes
What does more melanin give
Uv protection
How do you have more melanin
Having more MSH receptors and
What makes more MSH and receptors
Uv
What makes hair lighten
Destruction of melanin
What are oncogenes
Codes for proteins that simulates transition between cell cycle stages
What happens if a gene has less methylation
It is continuously active
What are tumour suppressor genes
Stop the cell cycle by producing proteins. Methylation turns gene off.
What is p53
Stops the enzyme that allows g1 to s1 stage
