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biology > cell division 2.1.6 > Flashcards

cell division 2.1.6 Flashcards

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1
Q

what is a haploid ?

A

a cell with a single set of unpaired chromosomes

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2
Q

what is a diploid ?

A

a cell with two complete set of chromosomes

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3
Q

what is a gamete ?

A

a sex cell

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4
Q

what is a zygote ?

A

formed when two gametes fuse together

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5
Q

what is a mutation ?

A

a change in organisms DNA

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6
Q

what is mitosis ?

A

cell division that produces identical daughter cells in eukaryotic cells (prokaryotic cells use binary fission)

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7
Q

what is meiosis ?

A

cell division that results in 4 haploid daughter cells

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8
Q

what is the significance of mitosis ?

A

growth of multicellular organisms - 2 daughter cells are genetically identical with the same number of chromosomes as parents , this enable unicellular zygotes to grow into multicellular organisms
replacement of cells + repair of tissues - dead cells are continuously replaced by identical cells
asexual reproduction - reproduction from one parent to usually create an identical offspring

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9
Q

what is chromatin ?

A

a combination of the slightly negative DNA wrapped around the slightly positive histones
decondensed chromatin is long and thin and can be easily accessed by cellular machinery for growth and function.
condensed chromatin condensed into chromosomes when the cell is about to divide

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10
Q

how many chromosomes ae in a human cell ?

A

46 chromosomes in 23 homologous pairs, one from the mother one from the father

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11
Q

what are the stages of the cell cycle ?

A

interphase ( G1,S,G2 )
mitosis ( prophase, metaphase, anaphase, telophase )
cell division ( cytokinesis )

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12
Q

what happens in interphase G1 ?

A

the first growth phase
cells grow and increase in size
transcription of genes to make RNA occurs
organelles duplicate
biosynthesis - protein synthesis to making the enzymes needed for DNA replication in the S phase

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13
Q

what happens in interphase S phase ?

A

synthesis phase = chromosomes replicate

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14
Q

what happens in interphase G2 ?

A

second growth phase
special chemicals ensure that the cell is ready for mitosis by stimulating proteins hat will be involved in making chromosomes condense and in formation of the spindle
cells continue to increase in size
energy stores are increased

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15
Q

what happens in interphase G0 ?

A
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16
Q

what happens in mitosis prophase ?

A

chromatin condenses and chromosomes become visible
centrioles move to poles
microtubules start to form spindle fibres
nuclear envelope and nucleus break down

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17
Q

what happens in mitosis metaphase ?

A

spindle fibres connect to the centromere
chromosomes align along the equator of the cell

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18
Q

what happens in mitosis anaphase ?

A

centromeres divide as chromatids are separated
chromatids are separated and are pulled to opposite sides by the shortening of spindle fibres
they make a v shape when they are pulled through the cytosol

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19
Q

what happens in mitosis telophase ?

A

chromosomes are assemble at each pole and nuclear envelope reforms around the, nucleus reforms
spindle fibres disintegrate
cytokinesis begins

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20
Q

what happens in cytokinesis ?

A

animal cells: a cleavage furrow forms around the middle of the cell as the cell membrane is pulled in my the cytoskeleton
plant cells: the presence of the cell wall prevents a cleavage furrow, vesicles from the Golgi apparatus form along the equator, vesicles fuse and divide the cell in two, new cell walls form

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21
Q

what are the differences between what is made in mitosis and mitosis ?

A

mitosis - produces somatic body cells
for growth, tissue repair, asexual reproduction
produces diploid cells
meiosis - produces gametes ( sex cells )
leads to genetic variation in offspring
haploid cells from diploid cells

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22
Q

briefly explain what happens in meiosis 1?

A

meiosis 1 - reduction division
homologous chromosomes are separated and placed in different cells
2 haploid cells made

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23
Q

briefly explain what happens in meiosis 2?

Study These Flashcards
A

meiosis 2 - similar to mitosis
sister chromatids are pulled apart at the centromere
one is placed in each daughter cell
it results in four haploid gametes

24
Q

what happens in meiosis prophase 1 ?

Study These Flashcards
A

chromosomes condense
centrioles move to poles and spindle fibres form
nucleus and nuclear envelope break down
homologous chromosomes pair up to form bivalents
crossing over occurs

25
what happens in meiosis metaphase 1 ?
homologous chromosomes line up on the equator spindle fibres attach to the centromere independent assortment
26
what happens in meiosis anaphase 1 ?
spindle fibres shorten chromosomes are pulled apart to opposite poles the chromatids stay joined together
27
what happens in meiosis telophase 1 ?
the chromosomes reach the poles nucleus evelope reforms chromosomes uncoil into chromatin
28
what happens in meiosis prophase 2 ?
chromosomes condense centrioles move to opposite ends of the cell forming a spindle fibres nucleolus and nuclear envelope
29
what happens in meiosis metaphase 2 ?
the individual chromosomes line up along the equator of the cell independent assortment
30
what happens in meiosis anaphase 2 ?
spindle fibres shorten the chromosomes are pulled apart to opposite poles centromere divides
31
what happens in meiosis telophase 2 ?
the chromosomes reach the poles of the cell the nuclear envelope reforms the chromosomes uncoil into chromatin then cytokinesis
32
what is crossing over ?
homologous chromosomes cross over in a point called the chiasma ( in prophase 1 ) synapse is the process forming a bivalent EXCHANGE IN GENETIC INFORMATION = NEW COMBONATION OF ALLELES
33
what is independent assortment ?
when the pairs randomly assort on the centre, sometimes they will be paternal (father) sometimes maternal (mother) when they get pulled apart either cell could have either chromosome
34
what is random assortment ?
each sperm is genetically different and is completely random which sperm fertilizes the egg
35
what are the human organ systems ?
muscular, skeletal, circulatory, nervous, lymphatic, endocrine, digestive, urinary, reproductive
36
what are the types of plant tissues ?
dermal tissue = epidermis, stomata ground tissue = parenchyma, collenchyma, sclerenchyma vascular tissue = xylem, phloem
37
what are plant organ systems ?
shoot system = leaves, flowers and stems root system = anchor the plant and to absorb minerals
38
what is differentiation ?
the process of a cell becoming specialised
39
what are stem cells ?
undifferentiated, unspecialised cells with the potential to differentiate into a variety of cells types within the organism
40
what are the sources of stem cells ?
embryonic stem cells adult stem cells - bone marrow induced pluripotent cells - developed in labs umbilical cord stem cells plant meristem cells
41
when a cells becomes differentiated what ability does it loose ?
the ability to divide it leaves the cell cycle (G0)
42
why does the speed of division need to be controlled ?
too slow leads to aging too fast leads to tumor development
43
what are the levels of stem cell potency ?
level 1: totipotent = can differentiate into any type of cell ( including extra-embryonic tissues like umbilicus ) and can produce an entire organism level 2 : pluripotent = can differentiate into all type of tissues but not whole organisms, present in early embryos level 3 : multipotent = can form a range of cells within a certain type of tissue eg haematopoietic celling in bone marrow -> blood cells
44
what are embryonic stem cells ?
they form a blastocyst with the outer cells in a layer ( trophectoderm ), embryonic stem cells form the inner cell mass. the inner cell mass is extracted and cultured in a lab with nutrients
45
what are uses of embryonic stem cells ?
understanding how diseases develop testing drugs in the labatory
46
what can adult stem cells differentiate ?
47
what is the function of erhtrocytes ?
carry oxygen from the lungs to respiring cells
48
how are erthrocytes adapted to their function ?
very small, biconcave and have a large surface area to volume ratio to allow for oxygen to diffuse across the membrane they are flexible, and developed cytoskeleton to allow them to twist into small capillaries most of their organelles are lost in differentiation including nucleus, mitochondria, endoplasmic reticulum to make more space for haemoglobin molecules
49
what is the function of neutrophils ?
white blood cell - ingest invading pathogens ( phagocytosis )
50
how are neutrophils adapted to their function ?
twice the size of erythrocytes, and they have a multilobed nucleus they are attracted to and travel towards he site of infection by chemotaxis
51
what is the function of epithelial cells ?
covers and lines free surfaces in the body eg. skin, cavities of digestive and respiratory issues, blood vessels two types: squamous epithelial cells are flattened in shape ciliated epithelial cells
52
what are the adaptations of epithelial cells ?
cells are close together and form continues sheets, adjacent cells are bound togethers by lateral contacts such as tight junction and desmosomes no blood vessels within epithelial tissue, cells receive nutrients by diffusion from tissue fluid int he underlying connective tissue
53
what is the function of a sperm cell ?
to fertilise the egg cell
54
how are sperm cells adapted to their function ?
many mitochondria carry out aerobic respiration, the ATP provides energy for the undulipodia to propel it forward small the thin to move easy enzymes are released once it reaches the ovum to allow it to enter the head contains the haploid make gamete nucleus and very little cytoplasm
55
what is cartilage tissue ?
is a connective tissue found in the outer ear, nose and the end of bones. it contains fibres of the proteins elastin and collagen. cartilage is firm flexible connective tissue composed of chondrocyte cells embedded in a extracellular matrix. it prevents the ends of bonds from rubbing together and causing damage.
56
how is squamous epithelium adapted ?
made up of specialised squamous epithelium cells, very flat and thin, one cell thick, allows for rapid diffusion. so if found lining the lungs
57

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