BIOLOGY EXAM REVISION Flashcards
what is the cell cycle?
The cell cycle is a complex process for cells to ensure exact mechanisms that genetic information can be passed without error from one cell to two daughter cells of the next generation.
It is through the cell cycle that somatic cells of eukaryotes can divide, providing two daughter cells from one parent cell.
what is sexual and asexual reproduction?
sexual reproduction is a method of producing offspring in which an egg and a sperm fuse to form a zygote.
asexual reproduction is a method of producing offspring that does not involve the fusion of different gametes, for example, binary fission.
what is cell growth differentiation
cell growth differentiation is the process of cells becoming specialized as their body develops.
what is a genome?
a genome is the total of the genes present in a cell or an organism.
what is a gene?
a gene is a unit of heredity that Is passed down from parent to an offspring and is held and passed down from generation to generation
what are alleles?
an allele is the different forms of a particular gene
what is a chromosome?
A chromosome is a long DNA molecule that has part of all of the genetic material of an organism.
what are the types of asexual reproduction?
The three main types of asexual reproduction are
Binary Fission,
Budding,
and Fragmentation.
Each type is used in different ways for different organisms.
what are the disadvantages of asexual reproduction?
Some disadvantages of asexual reproduction are- Offspring are genetic clones.
negative mutation: negative mutation can make sexually produced organisms susceptible to disease and can destroy large numbers of offsprings.
another is that asexual reproduction produces offspring that are close together and this causes them to compete for food and space.
what are the disadvantages of sexual reproduction?
Energy must be consumed to find a suitable mate.
Mutations may occur not as rapid and efficient as other forms of reproduction
what are the types of sexual reproduction?
Two different sexes male and female take part in the process
what are genetic crossovers?
genetic crossovers refer to predicting the outcomes of classical monohybrid crosses and test crosses
what happens in G1 phase (gap 1 )
the cell grows in size and synthesizes mRNA and proteins in preparation for subsequent steps leading to mitosis.
what happens in the s phase?
the s phase also known as the synthesis stage
The cell’s DNA replicates, ensuring that future cells obtain similar copies of its hereditary material,
and proteins associated with DNA are produced during this phase
what happens in the G2 phase? (gap 2)
During the G2 stage of interphase,
cells grow in preparation for division.
the synthesis of proteins occurs,
including those that form the microtubules of the spindle.
By the end of interphase, the cell has doubled its size.
what happens in the m phase?
Cell growth and protein production stop at this stage in the cell cycle.
All of the cell’s energy is focused on the complex and orderly division into two similar daughter cells
Mitosis is much shorter than interphase, lasting perhaps only one to two hours
what is an advantage of sexual reproduction
an advantage is that it increases in biodiversity
what order is the cell cycle?
It is divided into 2 major phases: interphase, mitotic phase.
under the interphase, the order goes
G1
s
G2
it reaches mitotic phase the order goes prophase metaphase anaphase telophase
what is a stem cell?
A stem cell is an unspecialized cell that can divide without limit as needed and can, under specific conditions
what does the term genetic screening refer to and what are the purpose of genetics screening and list some advantages and disadvantages.
genetic screening refers to the study of a person DNA in order to identify their genetic differences or susceptibility to different diseases and or abnormalities
the purpose of genetic screening is to act as an important tool of modern preventive medicine
on advantage is that people can receive their test results and be relived from their uncertainty
a disadvantage is that Testing does not eliminate a person’s risk for cancer.
what is some types of stem cells?
Embryonic stem cells.
Tissue-specific stem cells.
Mesenchymal stem cells.
Induced pluripotent stem cells.
compare embroyic stem cells and somatic stem cells
The difference between embryonic and somatic stem cells is that embryonic stem cells have the potential to differentiate into all cell types of the body, as they are pluripotent stem cells
where are stem cells found?
stem cells can be found in many different tissues In the body which includes the brain, blood, bone marrow, muscle, skin, heart, and liver tissues.
what is mitosis?
mitosis is a type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus,
what is meiosis?
meiosis is a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell,
what is the difference between meiosis and mitosis?
The difference between mitosis and meiosis is that
mitosis is a standard part of the cell cycle, the process that ensures DNA gets duplicated and shared to two daughter cells when a cell replicates
whereas meiosis only occurs when a gamete, a sex cell is made
how many chromosomes does a human have?
humans have 46 chromosomes
what are some main events that occour in meiosis I and II
the main event that occurs in meiosis I is that Homologue pairs separate during the first round of cell division
and the main event that occurs in meiosis II is that Sister chromatids separate during
what is a cross over (meiosis)
Crossing over is a biological occurrence that happens during meiosis when the paired homologs, or chromosomes of the same type, are lined up
what is the disjunction/nondisjunction in meiosis?
Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during cell division.
There are three forms of nondisjunction
failure of a pair of homologous chromosomes to separate in meiosis I
failure of sister chromatids to separate during meiosis II,
and failure of sister chromatids to separate during mitosis.
Nondisjunction results in daughter cells with abnormal chromosome numbers.
explain error checking during the cell cycle
error checking in the cell cycle happens at all the checkpoints
identify the stages in embryonic development
Zygote
morula
blastula
gastrula
embryo.
what are the differences between zygote, embryo and foetus
the difference between the terms is that zygote is what the baby is called right after an egg and sperm have been fused,
embryo refers to what the baby is called from the moments two cells exist
and the foetus is what the baby is called when the baby is unborn
what are the stages of mitosis?
interphase, prophase, metaphase, anaphase and telophase.
what happens in interphase?
genes in the DNA are read to make proteins. For that to happen,
the DNA must be expanded that is uncondensed.
the DNA is replicated.
what happens in prophase?
prophase is the longest phase. During prophase, chromatin condenses into chromosomes, and the nuclear envelope breaks down.
what happens in metaphase?
in metaphase, the chromosomes line up in the centre of the cell and then the spindle fibres attach to the centromeres.
what happens in anaphase?
Anaphase begins when the duplicated centromeres of each pair of sister chromatids separate
and the now-daughter chromosomes begin moving toward opposite poles of the cell due to the action of the spindle.
At the end of anaphase, a complete set of chromosomes
has assembled at each pole of the cell.
what happens in telophase?
telophase the last stage in which the separated chromosomes reach the opposite poles of the dividing cell and the nuclei of the daughter cells from around the two sets of chromosomes.
what is the function of the spindle?
Spindle fibres divide the genetic material in a cell.
The spindle divides the chromosomes in the parent cell equally into two daughter cells during both mitosis and meiosis.
what is the chromosome number in mitosis?
46 chromosomes
what is a monohybrid cross?
A monohybrid cross is a cross between two organisms with different variations at one genetic chromosome of interest
The character being studied in a monohybrid cross are governed by two or multiple variations for a single locus.
whats an autosome?
An autosome is any chromosome that is not a sex chromosome.
whats a karyotype?
Karyotyping is the process by which photographs of chromosomes are taken in order to determine the chromosome complement of an individual, including the number of chromosomes and any abnormalities.
whats a sex chromosome?
A sex chromosome, is a chromosome that differs from an ordinary autosome in form, size, and behavior.
what pairs in DNA?
a-t
g-c
